1.
one's forties; the forties (age range)
The age range from 40 to 49 years old. Used to describe a person's approximate age or to refer to this demographic group as a whole. In Japan this is often regarded as the period of peak responsibility at work and in the household.
This product was developed with women in their forties as the target market.
Forms
四十 ('forty') + 代 ('generation; age bracket'). Follows the standard decade pattern: 二十代, 三十代, 四十代, 五十代, etc. The reading is always よんじゅうだい — not しじゅうだい, because 四 is avoided as a homonym of 死 ('death') in age expressions.
Usage
- 四十代前半: early forties (40-44)
- 四十代半ば: mid-forties (around 45)
- 四十代後半: late forties (46-49)
- Very common in marketing, health articles, and demographic commentary. The forties are culturally seen as 働き盛り ('prime working years'), often with peak responsibilities at work and at home.
- In older literature, 四十路 is a poetic alternative, but 四十代 is the standard modern term in speech, print, and statistics.
- Unlike 四十歳 ('forty years old'), 四十代 refers to the entire decade rather than a specific age.