baby

baby — noun

1. a child in the first year or two of life, before they can walk on their own or s

1.nounA1
Definition

a child in the first year or two of life, before they can walk on their own or speak in full sentences.

Example

Mei rocked the baby in her arms until he fell asleep.

rock + the baby (in arms)

Lucas and Priya are expecting their first baby in March.

expecting + a baby (pregnancy)

Common collocations
  • newborn baby
  • premature baby
  • rock the baby
  • feed the baby
  • the baby is sleeping
Synonyms
  • infant

    more formal or medical; common in clinics and official forms

  • newborn

    specifically a baby in the first weeks after birth

  • little one

    warm, informal; often used by parents and relatives

Antonyms
  • adult

    fully-grown person, opposite end of the age scale

Grammar Patterns

have a baby

newborn baby

Usage Note

Often used with possessives or articles (the baby, our baby, her baby). 'Baby' can be paired with names of family roles (baby brother, baby sister) — those are the noun followed by another noun, not the adjective sense.

Common Mistakes

My sister had a baby boy yesterday, he is two years old.
My sister had a baby boy yesterday; he is one day old.
once a child can talk and walk freely, English speakers usually call them a toddler or child, not a baby.
She is a baby girl of fifteen.
She is a teenage girl of fifteen.
'baby girl' refers to a female infant, not a young teenager.

2. a recently born or very young animal that still depends on its mother for food a

2.nounA2
Definition

a recently born or very young animal that still depends on its mother for food and protection.

Example

The baby elephant stayed close to its mother as the herd crossed the river.

baby + animal name

Ranger Diaz showed the children a baby owl that had fallen from its nest.

Common collocations
  • baby elephant
  • baby bird
  • baby chick
  • baby tiger
  • feed a baby + animal
Synonyms
  • young

    as a noun ('the young of a species'); more formal, used in nature writing

  • newborn

    for very recently born animals

Grammar Patterns

a baby + animal name

Usage Note

For many species there is also a special name (kitten, puppy, calf, foal, cub, chick). 'Baby + animal' is the everyday way to refer to the young of any species, especially when the special term is unfamiliar to learners.

Common Mistakes

A baby cow is called a baby.
A baby cow is called a calf.
most farm animals have specific names for their young; 'baby cow' is informal but understandable.

3. an older child or grown-up who cries, whines, or sulks over small problems, the

3.nounB1
Definition

an older child or grown-up who cries, whines, or sulks over small problems, the way a much younger child would.

Example

Don't be such a baby — the cut on your knee is tiny.

Don't be such a baby (rebuke)

Citlali called his older brother a baby for refusing to go on the roller coaster.

Common collocations
  • be a baby about something
  • act like a baby
  • cry like a baby
  • stop being a baby
Synonyms
  • crybaby

    fixed compound; even more dismissive, often heard between children

  • wimp

    informal; focuses on cowardice rather than whining

Antonyms
  • grown-up

    as a contrast: 'act like a grown-up, not a baby'

Grammar Patterns

call somebody a baby

be such a baby

Usage Note

Used to criticise or tease, never as a compliment. Distinguish from sense 1: this sense applies to people clearly old enough to know better. The phrase 'cry baby' is a fixed insult that draws on the same idea.

Common Mistakes

You are baby for being scared.
You are such a baby for being scared.
this sense needs an article and usually 'such': 'be a baby' or 'be such a baby'.

4. within a family, team, or other close group, the person born last or admitted la

4.nounB1
Definition

within a family, team, or other close group, the person born last or admitted last — for instance, the last-born among brothers and sisters, or the newest player on a sports team — affectionately kept as that label long after they have grown up.

Example

At forty-two, Olivia is still the baby of the Hayashi family.

the baby of the family

Rookie pitcher Diego is the baby of the team and gets gentle teasing in the dugout.

the baby of the team

Common collocations
  • the baby of the family
  • the baby of the group
  • the baby of the team
Synonyms
  • youngest

    neutral and exact; without the affectionate tone

Antonyms
  • eldest

    the oldest member of the same group

Grammar Patterns

the baby of the family / team / group

Usage Note

Almost always appears with 'the' and 'of (a group)'. The person can be any age — what matters is being youngest within the named group. Distinguish from sense 1, which is about literal age.

Common Mistakes

He is the baby in the family, he is forty.
He is the baby of the family
he is forty but the youngest of five children.' — use 'of' to introduce the group.

5. a loving name people use for a partner, sweetheart, or romantic interest, often

5.nounB1
Definition

a loving name people use for a partner, sweetheart, or romantic interest, often instead of using their first name.

Example

Nia kissed her boyfriend's forehead and whispered, 'Goodnight, baby — drive safely.'

vocative use between partners

Aiden whispered, 'I missed you, baby,' as he hugged his wife at the airport.

Common collocations
  • hey baby
  • my baby
  • love you, baby
  • goodnight, baby
Synonyms
  • honey

    very common between partners; less sexual, also used to children

  • sweetheart

    warm and slightly old-fashioned; broader than romantic use

  • darling

    more British; can be romantic or merely friendly

Grammar Patterns

used as a vocative: Hey, baby

Usage Note

Strongly tied to romantic relationships. From a stranger — especially a man to a woman he doesn't know — it can sound rude or harassing rather than friendly. Use only with partners or in song lyrics.

Common Mistakes

Excuse me, baby, where is the train station?' (to a stranger).
Excuse me, where is the train station?
calling a stranger 'baby' often sounds disrespectful or flirtatious in an unwanted way.

6. a project, plan, or invention that one person started, cares about deeply, and f

6.nounB2
Definition

a project, plan, or invention that one person started, cares about deeply, and feels personally responsible for, often as if it were their own child.

Example

The community garden is Mrs. Camille's baby — she has been tending it for twenty years.

X is somebody's baby (project)

The new payment app was Rafael's baby, so he stayed late every night to fix the bugs himself.

Common collocations
  • it's her baby
  • his pet baby
  • the project is somebody's baby
Synonyms
  • brainchild

    focuses on the idea or invention rather than ongoing care

  • pet project

    very close in meaning; emphasises personal favourite, not always created by the person

Grammar Patterns

somebody's baby = their project

Usage Note

Almost always preceded by a possessive (his / her / Nia's). The thing is usually something the person founded, designed, or championed against opposition. Carries warm, slightly protective feeling — using it about someone else's project can sound dismissive of your own role.

Common Mistakes

The annual report is the baby of the team.
The annual report is the team's baby.
with this sense the possessive comes before 'baby', not as 'of' phrase.

7. a machine, vehicle, weapon, or other object that the speaker thinks is impressiv

7.nounC1
Definition

a machine, vehicle, weapon, or other object that the speaker thinks is impressive, powerful, or fun to use, talked about with pride or excitement.

Example

Watch this baby fly — the new drone can stay up for forty minutes.

watch / look at / try this baby (object showcase)

Officer Kim patted the patrol car's hood and grinned: 'This baby does zero to sixty in five seconds.'

Common collocations
  • this baby
  • watch this baby
  • fire up this baby
  • drive this baby
Synonyms
  • beauty

    very close: 'this beauty' / 'this baby'; both express admiration

  • beast

    stresses raw power rather than affection

Grammar Patterns

that baby = that object

Usage Note

Strongly informal and slightly masculine in flavour; often heard in adverts, sales pitches, and movie dialogue about cars, gadgets, and gear. Almost always with 'this', 'that', or 'these'.

Common Mistakes

Look at the baby, my new printer.
Look at this baby
my new printer.' — the demonstrative 'this/that' is essential; 'the baby' would be misread as a real infant.
Idioms

to lose or get rid of something good or useful while trying to remove the unwanted parts.

Cancelling the whole training programme over one bad workshop is throwing the baby out with the bathwater.

Reform the rules where they fail, but don't throw the baby out with the bathwater.

to walk away from a problem or task and suddenly leave someone else to deal with it alone.

When the manager quit mid-project, she left her assistant holding the baby.

The two partners disappeared on holiday and left Henry holding the baby at the office.

to sleep deeply and peacefully through the whole night.

After the long hike, Naomi slept like a baby until sunrise.

The new mattress is wonderful — I slept like a baby last night.

used to say that something is extremely easy to do, often unfairly so.

Beating the rookie team at chess was like taking candy from a baby.

For an experienced thief, picking that old lock was like taking candy from a baby.

If something is your baby, you created it and you are responsible for it and care about it a lot.

The new marketing campaign is Sara's baby, so she works on it every day.

This software project was my baby, and I was sad to leave it.

To sleep very deeply and peacefully.

After the long hike, Diego slept like a log for ten hours.

Did you sleep like a baby last night in the quiet hotel room?

baby — verb

baby — adjective

Word family

Synonym discussion

Sense: noun/1

All five words name young human beings, but they pick different stages and tones. 'Baby' is the everyday word for a child too small to walk or talk on its own; it is warm, neutral in register, and used by parents, friends, and strangers alike. 'Infant' covers roughly the same age range but sounds formal or medical — you read it on hospital charts and government forms, not in lullabies. 'Newborn' narrows the focus to the first weeks after birth, often emphasising fragility. 'Toddler' begins where 'baby' ends, naming a child of about one to three who has just learned to walk. 'Child' is the broad umbrella term for anyone from infancy to early teens. Compare: 'The baby is sleeping' (cosy, home), 'The infant was admitted at 03:14' (clinical), 'Our newborn weighed 3.2 kg' (very recent birth), 'The toddler ran across the room' (already mobile).

Common collocations

Nouns

  • baby boy
  • baby girl
  • baby brother
  • baby sister
  • baby clothes
  • baby food
  • baby bottle
  • baby steps

Phrases

Prepositions

  • with (a baby)
  • for (the baby)
  • of (a group)

Etymology

Middle English (babe)Modern English (baby)

First recorded in late Middle English (around 1300) as a shortened, affectionate form of 'babe', which itself was probably an imitation of the early sounds 'ba-ba' that small children make. The added '-y' is the same diminutive ending found in words like 'kitty' and 'doggy', adding warmth. The verb sense ('to baby someone') appeared centuries later, in the early 1700s, by treating the noun as an action: to treat a person the way one would treat a baby.