Definition of "forties" in English

noun

1. plural of forty

noun

1. The decade of the 1840s, 1940s, etc.

   • My ma was born in the forties and my pa was born in the seventies.

2. The decade of one's life from age 40 through age 49.

   • They're both in their forties.

3. (temperature, rates, plural only) The range between 40 and 49.

   • What to wear when the weather is in the forties really depends on whether you're talking fahrenheit or celsius.

adjective

1. From or evoking the 41st through 50th years of a century (chiefly the 1940s).

   • Two forties aircraft sat forgotten in the hangar until they were rediscovered by two trespassing teens.