Bryan McAllister’s personal reference notebook
September 11, 2026Short & citedBlog
Civic Viewpoint.
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Kept by Bryan McAllister — short guides, clear facts, and the Canadian angle when it matters.
Everyday Life • Sociology

Adults

Adults are people or animals that have reached full maturity.

Updated September 11, 20261 min readCited sources

An adult is a fully grown human or organism. In law, adulthood typically begins at the age of majority, often 18, but varies by jurisdiction.

What it is

The term adult is used as both a noun and an adjective. It commonly refers to a fully developed person or organism, and can also mean something suitable for grown people.

Why it matters

Legal adulthood defines when a person is responsible for their actions, with the age of majority set by each jurisdiction. Biologically, an adult has reached sexual maturity and can reproduce.

Key details

In Canada, the age of majority is determined by provinces and territories and is not uniform. The word also labels content intended for mature audiences, often including explicit material.

In short

  • Refers to fully mature person or organism.
  • Legal age of majority varies by country and province.
  • In biology, adulthood means sexual maturity.
  • Also a label for mature content.
Canadian angle

In Canada, adulthood is commonly associated with the age of majority, which is determined by provincial and territorial law and is not the same everywhere.

Quick questions

What is an adult?
An adult is a fully grown or mature person or organism.
At what age is someone usually considered an adult?
In many countries, adulthood begins at 18, but the legal age of majority varies by jurisdiction.
What does adult mean on media labels?
It usually means the material is intended for mature audiences and may contain explicit sexual content.

Sources

  1. Merriam-Webster — https://www.merriam-webster.com/dictionary/adult
    Supports: Definitions of adult as fully developed, relating to adults, and dealing in explicitly sexual material
  2. Cambridge Dictionary — https://dictionary.cambridge.org/us/dictionary/english/adult
    Supports: Adult as a fully grown person or animal; age of 18 in English law; adult content meaning
  3. Cornell Law School Legal Information Institute — https://www.law.cornell.edu/wex/adult
    Supports: Legal definition of adulthood as reaching the age of majority and variation by jurisdiction
  4. Wikipedia — https://en.wikipedia.org/wiki/Adult
    Supports: Biological adulthood as sexual maturity and general discussion of legal and social meanings
  5. PubMed Central — https://pmc.ncbi.nlm.nih.gov/articles/PMC5382900/
    Supports: WHO-related definition of adulthood and distinction from adolescence