(thirties)
Frequency: The word is one of the 700 most common words in English.
1.
Thirty is the number 30.
NUM
2.
When you talk about the thirties, you are referring to numbers between 30 and 39. For example, if you are in your thirties, you are aged between 30 and 39. If the temperature is in the thirties, the temperature is between 30 and 39 degrees.
N-PLURAL
3.
The thirties is the decade between 1930 and 1939.
She became quite a notable director in the thirties and forties.
N-PLURAL: the N