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.
母は四十代だ。
My mother is in her forties.
四十代になって体力の衰えを感じ始めた。
Now that I'm in my forties, I've started to feel my stamina declining.
この商品は四十代の女性をターゲットに開発された。
This product was developed with women in their forties as the target market.
四十代後半になると、子育てが一段落する人も多い。
Once people reach their late forties, many find that the busiest phase of raising children has passed.
WORD FORMATION:
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.
SUBDIVISIONS:
- 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)
COMMON COLLOCATIONS:
- 四十代の男性/女性: man/woman in their forties
- 四十代向け: aimed at people in their forties
- 四十代になる: to turn forty (enter one's forties)
- 四十代のうちに: while still in one's forties
- 働き盛りの四十代: people in their prime working years in their forties
USAGE:
- 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.