IPA: /ˈtwɛntiˌsʌmθɪŋ/
KK: /ˈtwɛntiˌsʌmθɪŋ/
Referring to a person who is in their twenties, typically between the ages of 20 and 29.
Many twentysomethings are exploring their career options and personal interests.
A person who is between the ages of twenty and twenty-nine.
Many twentysomethings are starting their careers and exploring new opportunities.
Twentysomething is formed from "twenty" (from Old English "twentig", meaning two tens) and "something" (from Old English "sum", meaning some or a certain amount, combined with "thing", meaning an object or entity). The term refers to a person in their twenties, indicating an age range that is a certain amount of years in the twenties.
Think of 'twenty' as two tens and 'something' as a certain amount — together, they describe someone who is in their twenties.
No commonly confused words.