gas
gas — abbreviation
1. a medical operation that changes a person's physical features to match their gen
a medical operation that changes a person's physical features to match their gender identity — short for Gender-Affirming Surgery
Obi is saving money to have GAS, also known as gender-affirming surgery, next year.
abbreviation GAS stands for Gender-Affirming Surgery
The hospital’s new clinic offers GAS as part of its transgender healthcare programme.
After years of waiting, Quinn finally received approval for GAS at the city hospital.
Support groups help people prepare emotionally for what GAS involves.
- undergo GAS
- GAS procedure
- GAS clinic
- access GAS
- gender confirmation surgery
another term for the same procedure, emphasising confirmation rather than affirmation
- sex reassignment surgery
older, broader term; less preferred by many in the transgender community
Usage Note
GAS is used as an abbreviation in medical and healthcare contexts. The full form 'gender-affirming surgery' is more common in general writing.
gas — noun
1. a substance that fills any container it is put in, has no fixed shape or size of
a substance that fills any container it is put in, has no fixed shape or size of its own, and can spread freely through the air — for example, oxygen, hydrogen, or carbon dioxide
When water reaches one hundred degrees Celsius, it turns into a gas called steam.
collocation: turns into a gas
Helium is much lighter than air, so balloons filled with it float upward.
The old factory released a poisonous gas, and the nearby town had to be evacuated.
Rohan’s science project shows that carbon dioxide is a gas plants need to grow.
subject: science report
- poisonous gas
- toxic gas
- release gas
- produce gas
- compress gas
- gas pressure
- gas molecule
Usage Note
This is the core scientific sense. Water in solid, liquid, and gas form is a common classroom example to explain states of matter.
Common Mistakes
2. a fuel in the form of a gas that is burned to produce heat, used for cooking foo
a fuel in the form of a gas that is burned to produce heat, used for cooking food and heating buildings
Mizuki turned on the gas and lit the stove to boil water for tea.
collocation: turn on the gas
Many homes in this area use gas for heating during the cold winter months.
A strong smell of gas filled the kitchen, so Quinn opened all the windows immediately.
The plumber fixed a small leak in the gas pipe before it became dangerous.
collocation: gas pipe / gas leak
- gas stove
- gas heater
- gas pipe
- gas leak
- gas bill
- smell gas
- turn off the gas
- gas supply
- natural gas
the specific type of fossil fuel gas found underground, used for heating and cooking
Usage Note
In Taiwan, natural gas delivered through pipes is called 天然氣 or 焖氣; bottled gas for cooking is called 液化石油氣 (LPG). The word 'gas' alone in this sense is understood but the more specific Chinese term is used in daily life.
Common Mistakes
3. a type of gas that is breathed in by a patient prior to surgery, putting them to
a type of gas that is breathed in by a patient prior to surgery, putting them to sleep or stopping them from feeling any pain
Before the operation, the nurse gave Sirin gas through a mask to help her sleep.
passive: give someone gas through a mask
The dentist used gas to calm Cyrus’s nerves before pulling out his tooth.
Modern anesthetic gas is much safer than the gas used in hospitals a century ago.
A patient might wake up and feel severe pain without enough gas during surgery.
- give gas
- administer gas
- gas mask
- under gas
- anesthetic gas
- anaesthetic
the general term for any substance that causes loss of sensation or consciousness
- laughing gas
informal name for nitrous oxide, used especially in dentistry
Usage Note
In everyday English, 'gas' for medical anaesthesia often refers specifically to nitrous oxide (laughing gas) used by dentists. For major surgery, the word 'anaesthetic' is more common.
4. air or gas that builds up inside the stomach or intestines, sometimes causing pa
air or gas that builds up inside the stomach or intestines, sometimes causing pain, swelling, or the need to pass wind
After eating a bowl of beans, Quinn felt uncomfortable because of gas in his stomach.
collocation: gas in [body part]
The baby cried until her mother gently patted her back to help release the gas.
Some people get gas when they eat too fast or drink fizzy drinks.
The doctor told Sade to avoid foods that cause gas, such as cabbage and onions.
- have gas
- pass gas
- cause gas
- get gas
- feel gassy
- gas pain
- gas in the stomach
- wind
more common in British English for the same condition; 'I have wind' means the same as 'I have gas'
- flatulence
the formal medical term; rarely used in everyday conversation
Usage Note
In polite conversation, people often use phrases like 'have gas', 'pass gas', or 'feel gassy' rather than more direct words.
5. a liquid made from petroleum that is used as fuel for cars, trucks, and other ve
a liquid made from petroleum that is used as fuel for cars, trucks, and other vehicles with an engine
Christopher stopped at the station to put gas in his truck before the long drive.
collocation: put gas in [vehicle]
The price of gas went up by fifty cents a litre this week.
Sade’s car runs on gas, so she stops at a station every few days.
variety note: 'gas' US vs 'petrol' UK
A delivery truck uses more gas when it carries heavy loads up the mountain.
- run out of gas
- fill up with gas
- gas station
- gas tank
- gas pedal
- gas price
- a gallon of gas
Usage Note
This sense is standard in American English. In British English, the word 'petrol' is used instead. In Taiwan, people generally use 汽油 (qìhyóu) or 'petrol', but American English 'gas' is widely understood through media.
Common Mistakes
6. the control inside a car operated by pushing down with your foot, which causes t
the control inside a car operated by pushing down with your foot, which causes the engine to turn faster and the car to speed up
Gabriel pressed the gas gently as the traffic light turned from red to green.
collocation: press the gas
When Sade took her foot off the gas, the car slowed down smoothly.
The instructor told Élise to keep her foot steady on the gas going uphill.
Jason pushed the gas to the floor to pass the slow truck on the highway.
- step on the gas
- press the gas
- take your foot off the gas
- hit the gas
- gas pedal
- accelerator
the standard term in British English and formal driving instruction
- throttle
the engine part that controls fuel flow; used more for motorcycles and aircraft
- brake
the pedal that slows or stops the vehicle
Usage Note
The British English equivalent is 'accelerator' rather than 'gas' or 'gas pedal'. In everyday American speech, people also say 'step on it' or 'hit the gas' to mean speed up.
Common Mistakes
7. something or someone that is very funny, enjoyable, or entertaining to be around
something or someone that is very funny, enjoyable, or entertaining to be around
The comedy show last night was a real gas — the whole audience laughed non-stop.
informal slang: a real gas
The roller coaster ride with her cousins was a real gas; Mizuki wants to go again.
Grandpa told silly jokes all evening, and the children said he was a gas.
The school trip to the science museum was a real gas for everyone in the class.
- a real gas
- an absolute gas
- be a gas
Usage Note
This is an older slang expression from the 1950s-1960s. It is still understood but can sound dated or nostalgic. More common modern alternatives are 'a blast', 'a riot', or simply 'a lot of fun'.
Common Mistakes
8. a very fast pitch thrown by a baseball pitcher, making it hard for the batter to
a very fast pitch thrown by a baseball pitcher, making it hard for the batter to hit
The pitcher threw serious gas, striking out three batters in a row.
baseball slang: throw gas
Fans cheered when the rookie pitcher fired gas at ninety-five miles per hour.
At the baseball game, Esteban could not hit the pitcher’s gas no matter how he tried.
The crowd went wild when the pitcher started throwing gas in the final inning.
- throw gas
- fire gas
- pitcher’s gas
- hit the gas
Usage Note
This sense is used only in baseball contexts. It is not understood outside of sports discussions. The words 'heat' and 'smoke' are used similarly in baseball slang for fast pitches.
step on the gas
idiomto drive faster by pressing the accelerator pedal; also used figuratively to mean hurry up or work faster
We are going to be late for the movie — step on the gas!
The manager told the team to step on the gas and finish the project by Friday.
run out of gas
idiomto use up all the fuel in a vehicle so it stops moving; also used figuratively to mean losing energy or motivation to continue something
The car ran out of gas on the highway, and we had to call for help.
After studying for six hours straight, Cyrus completely ran out of gas and went to bed.
be cooking with gas
idiomTo be making good progress or performing very effectively.
Once Maya learned the new software, she was cooking with gas.
Are you cooking with gas now that you have the right tools?
gas — verb
1. to cause a person or animal to die, become very sick, or lose consciousness thro
to cause a person or animal to die, become very sick, or lose consciousness through the inhalation of poison gas
Thousands of soldiers were gassed in the trenches and many lost their lives.
passive: were gassed
The firefighters saved the family before smoke from the fire could gas them.
Workers at the chemical plant were accidentally gassed by a leak in the storage.
The cruel regime used poison gas to gas innocent people during the conflict.
- be gassed
- gas someone
- gas the enemy
- gassed to death
- asphyxiate
formal term meaning to cause death by preventing oxygen from reaching the body
- suffocate
to die from lack of air, not necessarily from a specific poisonous gas
Usage Note
This verb is most commonly found in the passive voice ('were gassed', 'get gassed') when describing historical events or accidents. It carries strong negative associations with war and chemical weapons.
Common Mistakes
2. to spend time talking with others at length, usually about subjects that are tri
to spend time talking with others at length, usually about subjects that are trivial or only for amusement, instead of getting down to work
The two friends sat on the porch and gassed for hours about their school days.
informal: gas + preposition 'about'
Sirin and Sade stood by the water cooler, gassing about weekend plans.
Stop gassing and get back to your desk — the deadline is tomorrow morning.
Mizuki gassed on the phone with her cousin until the battery on her phone died.
- gas about
- gas on the phone
- stop gassing
- gas for hours
Usage Note
This is an informal, somewhat old-fashioned verb. It can carry a mildly negative tone when someone is gassing instead of doing work. More neutral synonyms are 'chat', 'chatter', or 'gossip'.
Common Mistakes
Word family
- gaseousadjectiveB2
- gassyadjectiveB2
- gasifyverbC1
- gasificationnounC1
- gasolinenounB1
Synonym discussion
Sense: noun/1
Gas, vapour, steam, fume, and smoke all refer to airborne substances, but they differ in formation and context. Gas is the broadest term — any substance in the gaseous state, whether natural or artificial, visible or invisible (e.g., ‘oxygen is a gas’). Vapour is a gas that has risen from a solid or liquid, often visible as a mist (e.g., ‘water vapour rising from a hot bath’). Steam is specifically the vapour produced when water boils (e.g., ‘steam rising from a kettle’). Fume refers to gases that are strongly smelling and often unhealthy, typically from chemicals, paint, or engines (e.g., ‘car exhaust fumes’). Smoke comes from burning material and contains solid particles, so it is visible and has a characteristic smell (e.g., ‘smoke from a campfire’). In everyday use, ‘steam’ and ‘smoke’ have the most specific, recognizable sources; ‘vapour’ is slightly more technical; and ‘fume’ almost always carries a warning of danger.
Common collocations
Nouns
- gas station
- gas tank
- gas supply
- gas company
- gas industry
- gas price
- gas leak
Adverbs
Phrases
- a cloud of gas
- a form of gas
- a mixture of gases
- a shortage of gas
Prepositions
- of gas
- with gas
- by gas
- from gas
- without gas
Etymology
The word 'gas' was invented in the 1600s by the Flemish chemist Jan Baptist van Helmont. He adapted the Greek word 'chaos' (meaning empty space or disorder) because the behaviour of gases seemed chaotic compared to solids and liquids. The word entered English through scientific Latin and French. The specific sense of 'gasoline' emerged in the late 1800s as a trade name for petroleum-based fuel, and was later shortened to 'gas'. The slang sense meaning 'fun' appeared around the 1950s. The abbreviation GAS (gender-affirming surgery) is a 21st-century medical term unrelated to the older word.