Definition

A term used to describe the position of something that is number 30 in a sequence or series.

Example

She celebrated her thirtieth birthday with a big party.

Conversation

Hey, did you know today is the thirtieth of the month?

Really? Time flies so fast!

I know, right? It feels like we just started this month.

Yeah, and next month will be here before we know it.

Synonyms & Antonyms

Root Explanation

Thirtieth is formed from "thirty" (from Old English "þritig", meaning three times ten) and the suffix "-eth" (used to form ordinal numbers). The word "thirtieth" refers to the ordinal form of thirty, indicating the position in a sequence as the third decade.

Memory Tip

Think of 'thirty' as three times ten, and remember that 'thirtieth' means the position of being the third in a sequence of tens.

Visually Confused Words