How to say "slack" in Japanese

• 緩みゆるみCommon
  nounThe noun for physical slack or looseness — the play or give in a rope, belt, or mechanism. Use it when slack is a physical state or amount rather than a manner of behaving.
• 緩やかゆるやかJLPT N1approx.Common
  na-adjectiveAn adjective for things that are loose or slack in a gentle way rather than tight or steep — a gentle slope, a relaxed pace. For slack as a physical amount, use the noun 緩み.
• 怠けるなまけるJLPT N3approx.Common
  ichidan verb, intransitive verbThe verb 'to slack' in the sense of shirking: to be lazy or idle instead of doing the work or study one should. Said, for instance, of someone slacking off at work or school.
  概がいして人間にんげんは怠なまける傾向けいこうにある。↗

  As a rule, man is inclined to be lazy.
• スラックCommon
  nounThe loanword, borrowed straight from English 'slack'. Mostly seen in technical contexts, such as slack in a cable or rope; in everyday speech it is seldom the word you want.
• ルーズJLPT N1approx.Common
  na-adjectiveSlack as in lax or careless habits: a person sloppy about time, money, or keeping promises. It describes people and attitudes, not physical looseness, and usually carries a tone of disapproval.

Use 「緩み」 for physical slack or play, 「緩やか」 for things that are loose or gentle, 「怠ける」 for slacking off on work, 「スラック」 as the technical loanword, and 「ルーズ」 for people careless with time, money, or promises.

Usage comparisons are AI-assisted and cross-checked by multiple models; for study reference only

• 緩みゆるみslack
• 緩やかゆるやかloose
• 怠けるなまけるto be lazy
• スラックslack
• ルーズcareless (with something, esp. time, money, promises, etc.)
• だらしないslovenly (appearance, work, etc.)
• 低調ていちょうinactive
• 緩慢かんまんslow
• たるみslack
• でれっとslack
• 締まりのないしまりのないslack
• 緩かゆるかloose
• パッとしないunimpressive
• だらしのないslovenly (appearance, work, etc.)
• だらしがないslovenly (appearance, work, etc.)
• 閑散かんさんinactive (business, trade, etc.)
• 不景気ふけいきpoor (business)
• ちょろいsoft
• 暇ひまslow (business)