biological

biological — adjective

1. relating to plants, animals, and other living things, or to the way their bodies

1.adjectiveB2
Definition

relating to plants, animals, and other living things, or to the way their bodies grow, work, and reproduce.

Example

Dr. Mira studies the biological clock that tells birds when to migrate south.

biological + noun (clock, process, system)

Stress can cause real biological changes inside your body, not just in your mood.

biological changes / effects on the body

Common collocations
  • biological clock
  • biological process
  • biological function
  • biological sciences
  • biological diversity
Synonyms
  • physiological

    more technical; focuses on how the body works

  • organic

    broader; can also mean 'natural' or 'without chemicals'

Usage Note

Always before a noun in this sense. Distinguish from sense 2 (about family/birth relationships): here the focus is on bodies, cells, or scientific study, not on who someone's parent or child is.

Common Mistakes

My headache is very biological today.
My headache has a biological cause, probably low blood sugar.
'biological' describes processes, systems, or causes, not how strong a feeling is.

2. describing a parent, child, or other family member who is connected to you by bi

2.adjectiveB2
Definition

describing a parent, child, or other family member who is connected to you by birth, not through adoption or marriage.

Example

Yusuf was adopted as a baby and has never met his biological mother.

biological mother / father / parent — most common pairing

Although Sam raised the boys alone, he is not their biological father.

biological father in contrast with social/legal parent

Common collocations
  • biological mother
  • biological father
  • biological parent
  • biological child
  • biological sibling
Synonyms
  • natural

    older usage; 'natural mother' has a similar meaning

  • birth

    as in 'birth mother' — same idea, more common in adoption contexts

  • blood

    as in 'blood relative' — informal, emphasises shared ancestry

Antonyms
  • adoptive

    of a parent who legally takes someone as their child

  • foster

    of a temporary parent or family

  • step-

    as in stepmother, stepfather — through marriage, not birth

Usage Note

Always used before a noun and almost always with a close family word: mother, father, parent, child, son, daughter, sibling. Often signals a contrast with 'adoptive', 'step-', or 'foster'.

Common Mistakes

She is my biological friend.
She is my biological sister.
'biological' only fits family connections from birth, not friendships.

3. used about a person's sex when it is decided by features they are born with, suc

3.adjective
Definition

used about a person's sex when it is decided by features they are born with, such as their genes and the body parts used for having babies, rather than the gender they feel themselves to be.

Example

On the form, please write your biological sex as well as your gender identity.

biological sex contrasted with gender identity

Some sports leagues separate athletes by biological sex to keep competition fair.

biological sex in policy and sports contexts

Common collocations
  • biological sex
  • biological male
  • biological female
Synonyms
  • natal

    technical; means 'at birth' (as in 'natal sex')

Usage Note

Almost always pairs with the noun 'sex'. The phrase is sensitive: it appears mostly in medical, legal, or sports contexts where the writer wants to draw a clear line between body-based sex and a person's gender identity.

Common Mistakes

My biological gender is female.
My biological sex is female.
pair 'biological' with 'sex'; 'gender' refers to identity and roles, not body features at birth.

4. describing washing powders, soaps, and other cleaning products that contain natu

4.adjective
Definition

describing washing powders, soaps, and other cleaning products that contain natural body chemicals called enzymes to break down stains and dirt.

Example

Kalani switched to a non-biological detergent because the enzymes irritated her son's skin.

non-biological as the common opposite

Biological washing powder works best on grease, blood, and grass stains.

biological washing powder + types of stains

Common collocations
  • biological washing powder
  • biological detergent
  • biological liquid
Synonyms
  • enzyme-based

    more descriptive; explains the active ingredient

Antonyms
  • non-biological

    the same product without enzymes, marketed for sensitive skin

Usage Note

Mainly British English, mostly heard with 'washing powder', 'detergent', 'liquid', or 'soap'. Often appears alongside or in contrast with 'non-biological', the gentler version made for sensitive skin.

Common Mistakes

I bought a biological soap from the lab.
I bought a biological washing powder from the supermarket.
in this sense, it labels everyday cleaning products with enzymes, not lab chemicals.

5. describing weapons or attacks that spread germs, viruses, or other tiny living o

5.adjective
Definition

describing weapons or attacks that spread germs, viruses, or other tiny living organisms in order to kill people, animals, or food crops.

Example

United Nations inspectors searched the desert base for hidden biological weapons.

biological weapons — the most common pairing

Soldiers wore thick masks and suits to protect them from a possible biological attack.

biological attack / threat / agent

Common collocations
  • biological weapon
  • biological warfare
  • biological attack
  • biological agent
  • biological terrorism
Synonyms
  • germ

    informal; 'germ warfare' is the everyday phrase for biological warfare

  • bacteriological

    older, narrower term limited to bacteria

Usage Note

Almost always before nouns like 'weapon', 'warfare', 'attack', 'agent', 'threat', or 'terrorism'. Often grouped with 'chemical' and 'nuclear' (e.g. 'CBRN', short for chemical, biological, radiological, nuclear).

Common Mistakes

The country signed a treaty against biological tools.
The country signed a treaty against biological weapons.
'biological' in this sense pairs with words for warfare, not general 'tools' or 'devices'.

Word family

Synonym discussion

Sense: adjective/1

All four words describe living things, but they are not interchangeable. 'Biological' is the everyday choice for anything connected to life, bodies, or the science of biology — a biological clock, biological diversity. 'Physiological' is more technical and zooms in on how a healthy body actually works: heart rate, breathing, hormones; doctors prefer it over 'biological' when discussing function. 'Organic' is much broader: in chemistry it means 'containing carbon', in everyday speech it often means 'grown without artificial chemicals' (organic vegetables), so it can confuse readers. 'Biotic' is a specialist ecology word, almost only seen in pairs like 'biotic factor' or 'abiotic environment'. So a textbook talks about biological processes, a clinic measures physiological responses, a farmer sells organic carrots, and an ecologist studies biotic communities.

biological ↗physiological ↗organic ↗biotic

Common collocations

Nouns

Adverbs

  • purely biological
  • strictly biological
  • essentially biological

Phrases

  • biological clock is ticking
  • biological and chemical weapons
  • biological sex versus gender

Prepositions

  • biological in origin
  • biological to humans

Etymology

Ancient GreekModern LatinGerman/FrenchEnglish

'Biological' joined English in the early 1800s as the adjective form of 'biology', a word coined a few years earlier in German and French scientific writing. Its building blocks come from Ancient Greek: 'bios' meaning 'life' and '-logia' meaning 'study of', plus the English ending '-ical'. So 'biological' literally means 'having to do with the study of life'. The newer senses — about birth parents, body-based sex, enzyme cleaners, and germ warfare — all developed during the 20th century as scientists, lawyers, and the general public needed quick ways to talk about life processes in everyday situations.