How to say "careless" in Japanese

• ルーズJLPT N1approx.Common
  na-adjectiveCareless as a settled attitude — with time, money, or promises — rather than a single slip: the person is lax or slack by habit. Think of a colleague who is always late.
• ずさんCommon
  na-adjective, nounCareless in the sense of sloppy and faulty: work, plans, or management done without proper care, so that mistakes result. Typical context: slipshod accounting or planning that later proves full of errors.
  トニーは人ひとを雇やとい、もっと客きゃくを掴つかみ、仕事しごとをより早はやくずさんにやれば、もっと金かねもうけができると思おもったのだ。↗

  Tony realized that if he hired another crew, got more customers and did the job quicker and sloppier, he could make more money.
• 滅多めったCommon
  na-adjectiveSeldom the word you want for plain 'careless': its rash, thoughtless sense survives almost only in set phrases like 滅多なことはしない 'would never do anything rash', and 滅多に…ない means 'hardly ever'.
• おろそかJLPT N1approx.Common
  na-adjectiveCareless as neglect: failing to give a duty, task, or person the attention it deserves. Typical context: someone who lets work, study, or daily duties slide — remiss rather than accident-prone.
  学業がくぎょうをおろそかにするなんて、君きみはばかだ。↗

  It is silly of you to neglect your studies.
• そそっかしいJLPT N2approx.Common
  i-adjectiveCareless through haste: describes a person who acts too quickly and is forever making small slips — dropping things, forgetting, spilling. It paints the person's nature, not the quality of finished work.
  バスに傘かさを忘わすれるとは彼女かのじょはそそっかしい。↗

  It was careless of her to leave her umbrella in the bus.

Use 「ルーズ」 for habitual laxness about time, money, or promises; 「ずさん」 for sloppy, faulty work; 「おろそか」 for neglecting a duty; 「そそっかしい」 for a hasty, error-prone person; 滅多 is mainly fixed-phrase material.

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

• ルーズcareless (with something, esp. time, money, promises, etc.)
• ずさんcareless
• 滅多めったthoughtless
• おろそかnegligent
• そそっかしいcareless
• 軽率けいそつrash
• ぞんざいrough
• いい加減いいかげんirresponsible
• のんきeasy
• だらしないslovenly (appearance, work, etc.)
• 軽々しいかるがるしいrash
• うかつcareless
• 粗忽そこつcareless
• 杜漏ずろうcareless
• 孟浪もうろうcareless
• 投げやりなげやりnegligent
• ゆるがせnegligent
• 不用心ぶようじんunsafe
• 粗放そほうrough
• いけぞんざいrude
• ええ加減ええかげんirresponsible
• 至らないいたらないimperfect
• ふつつかinexperienced
• 無頓着むとんちゃくindifferent
• 軽佻けいちょうflippant
• だらしのないslovenly (appearance, work, etc.)
• だらしがないslovenly (appearance, work, etc.)
• 至らぬいたらぬimperfect
• 大雑把おおざっぱcareless (e.g. work)
• 乱暴らんぼうrough (handling, language, etc.)
• 不用意ふよういcareless
• 上滑りうわすべりfrivolous
• 適当てきとうperfunctory
• 安易あんいeasygoing
• 荒っぽいあらっぽいrough (e.g. work)
• 底抜けそこぬけimprudent
• 無造作むぞうさcasual
• 安やすrash
• かりそめcareless
• 尻が軽いしりがかるいcareless
• 草々そうそうrough
• 尻軽しりがるrash