adulthood
n. uncountable B1 Intermediate US //əˈdəɫtˌhʊd// UK //ɐdˈʌlthʊd// adult·hood
n. the part of your life when you are a fully grown adult. It usually starts when you are 18 or 21 and have legal responsibilities.
n. the period of time in a person's life when they are fully developed and mature. Refers to the state of being an adult, often defined by legal age or social milestones.
Most people look forward to the freedom of adulthood.
Moving into your own apartment is often seen as the first real step into adulthood.
The transition from adolescence to adulthood is marked by a significant shift in legal status and the expectation of financial self-sufficiency.
From adult + -hood.
Usage
Uncountable when referring to the general state or period of life; rarely used in the plural.