後|あとato[1]atamadaka (head-high)

1. no-adjectivebehind; rear
   少女しょうじょたちのうち一人ひとりが後あとに残のこされた。↗

   One of the girls was left behind.
2. no-adjectiveafter; later
   雨天うてんの後あとには晴天せいてんが来くる。↗

   After rain comes fair weather.
3. no-adjectiveremainder; the rest
4. noun, adverbmore (e.g. five more minutes); left
   あと２通つう手紙てがみを書かかなくてはならない。↗

   I have another two letters to write.
5. noun, adverbalso; in addition
6. no-adjectivedescendant; successor; heir
7. no-adjectiveafter one's death
   藤ふじさんがあとに４人にんの子こを残のこして死しにました。↗

   Mr. Fuji died, leaving 4 children behind him.
8. no-adjectivepast; previous

• Synonym後方こうほうWrittenWritten/formal word for the rear or the space behind, as in 「後方を確認する」; unlike 「あと」 it never refers to time.
• Synonym背後はいごWrittenWritten/formal: behind someone or something, or behind the scenes, as in 「背後に人の気配」「事件の背後」; often carries a hidden, unseen nuance.
• Synonym裏側うらがわNeutralNeutral: the reverse side or the side hidden from view, as in 「月の裏側」; stresses the other side rather than position behind.
• Synonym後部こうぶWrittenWritten/formal word for the rear part of a vehicle or object, as in 「後部座席」; especially common for vehicles.
• Synonym背面はいめんWrittenWritten/formal: the back or reverse face of an object, and by extension a hidden side, as in 「背面跳び」.
• SynonymバックCasualColloquial loanword for the back, background or backing/support, as in 「バックする」 for reversing a car.
• Synonym後々あとあとNeutralNeutral word for the more distant future, as in 「後々のために」; reaches further ahead than 「あと」.
• Synonym後ろ側うしろがわNeutralNeutral word for the back side of an object; purely spatial, with no time sense.
• Related裏面りめんWrittenWritten/formal: the back or reverse of an object, or the hidden side of affairs, as in 「裏面に記入」「政界の裏面」; 「あと」 does not cover reverse sides.
• Related背中せなかCasualColloquial word for the back as a body part of people or animals; it only overlaps with 「あと」 in the sense of being behind.
• Related後々のちのちNeutralNeutral word for the more distant future, as in 「後々のために」; reaches further ahead than 「あと」.
• Related以後いごWrittenWritten/formal: from a given point in time on, as in 「十時以後」「以後気をつけます」; more formal than 「あと」.
• RelatedリアCasualColloquial loanword for the rear of a vehicle, mostly in compounds like 「リアウィンドウ」.
• Related背部はいぶWrittenWritten/formal term for the back of a person or thing, mostly in medical or technical writing; in everyday speech say 「背中」.
• Related後ほどのちほどWrittenA polite way to say 「後で」, as in 「後ほどご連絡します」; used in business and service settings.
• Relatedこの後このあとCasualColloquial expression for the time from a point onward, what comes next, as in 「この後どうする」.
• Related後であとでCasualColloquial adverb for doing something later, after a while, as in 「後で電話する」; very common in speech.
• Related後尾こうびWrittenWritten/formal word for the tail end of a line of people or vehicles, as in 「列の後尾」.
• Related後面こうめんWrittenWritten/formal word for the rear face of an object; rare in daily speech, where 「後ろ」 is used.
• Related後背こうはいWrittenWritten/formal word for the area behind or to the rear, used mostly as the first element of compounds like 「後背地」.
• Antonym先さきCasualColloquial antonym of 「あと」: the front or tip ahead, or an earlier point in time.
• Antonym前ぜんWrittenThe same word as the entry above, also written 「前」; identical in meaning as the opposite of 「あと」.

For time — after, later, or what remains — 「あと」 is the default. For a polite later use 「後ほど」, and for a formal from-now-on 「以後」. For space, the rear is 「後ろ」 or 「後方」, the reverse side is 「裏側」, and the rear of a vehicle is 「後部」. The body's back is 「背中」, behind the scenes is 「背後」, and 「先」 is the antonym for front or before.

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

1. （あと、のち）時間じかんの呼称こしょう。ある時点じてんに対たいして未来みらいとなる時点じてん。