Collins COBUILD Advanced Learner's English Dictionary - forty

(forties) Frequency: The word is one of the 700 most common words in English. 1. Forty is the number 40. NUM 2. When you talk about the forties, you are referring to numbers between 40 and 49. For example, if you are in your forties, you are aged between 40 and 49. If the temperature is in the forties, the temperature is between 40 and 49 degrees. He was a big man in his forties, smartly dressed in a suit and tie. N-PLURAL 3. The forties is the decade between 1940 and 1949. Steel cans were introduced sometime during the forties. N-PLURAL: the N