いっぱい・一杯・１杯・一盃ippai[0]heiban (flat)

1. no-adjectiveone cup (of); one glass (of); one bowl (of); cupful; glassful; bowlful; spoonful
   コップ１杯ばいの水みずをください。↗

   Give me a glass of water, please.
2. nounone drink (of alcohol)
   仕事しごとの後あとで、一杯いっぱいどう？↗

   How about going out for a drink after work?
3. na-adjective, no-adjective, noun (suffix)full; filled (with); brimming (with); crowded; packed
   列車れっしゃは乗客じょうきゃくでいっぱいだった。↗

   The train was full of passengers.
4. adverb, noun (suffix)fully; to capacity; to the maximum; as much as possible
   このボトルに水みずをいっぱい入いれてください。↗

   Please fill this bottle with water.
5. adverba lot; much; many
   彼女かのじょは香港ほんこんに友人ゆうじんがいっぱいいる。↗

   She has many friends in Hong Kong.
6. noun (suffix), adverball of ...; the entire ...
   たとえ一日ついたちいっぱい掛かかってもそのタイプを仕上しあげます。↗

   Even if it takes me the whole day, I will do the typing.
7. nounone (squid, octopus, crab, etc.)
8. nounone (boat)

• Synonym満杯まんぱいNeutralNeutral. A container or venue being full, e.g. 「駐車場が満杯」; describes the state objectively rather than the amount in one cup.
• SynonymフルCasualColloquial loanword for full capacity or maximum effort, mostly in compounds such as 「フル回転」「フルコース」; rarely replaces 「いっぱい」 on its own.
• SynonymぎゅうぎゅうCasualColloquial mimetic word for being packed and crowded, e.g. 「ぎゅうぎゅう詰めの電車」; adds a squeezed, crowded feel 「いっぱい」 lacks.
• Synonym満腹まんぷくNeutralNeutral but rather formal. Chiefly a full stomach after eating, as in 「満腹になる」; a more formal way to say one's stomach is 「いっぱい」.
• Synonym満タンまんタンCasualColloquial. Filling a tank or container to the top, as in 「ガソリン満タン」; also used figuratively for eating one's fill. Covers a narrower range than 「いっぱい」.
• SynonymパンパンCasualColloquial mimetic word for something stuffed bulging full, e.g. 「お腹がパンパン」; beware its separate old postwar slang sense.
• SynonymきちきちCasualColloquial. A schedule or space packed tight with no room to spare, e.g. 「予定がきちきち」; about tightness, not filled quantity.
• SynonymきゅうきゅうCasualColloquial. Crammed in very tightly; also describes a hand-to-mouth life as in 「きゅうきゅうの生活」, a use far from 「いっぱい」.
• SynonymギチギチCasualColloquial. Packed full with no gaps at all, with a taut, strained feel; about crowding, not the amount 「いっぱい」 covers.
• Related多量たりょうWrittenWritten/formal prose for a large quantity, e.g. 「多量の出血」「多量の水」; objective and stiff — in daily speech say 「たくさん」 instead.
• RelatedたくさんNeutralNeutral and the most common way to say 'a lot'; 「いっぱい」 stresses being filled to the brim, while 「たくさん」 just counts quantity.
• Related多くおおくNeutralNeutral but leaning written; means many or the greater part, e.g. 「多くの人」. About number, not the filled-to-the-brim sense of 「いっぱい」.
• Related多数たすうNeutralNeutral. A large number or the majority, e.g. 「多数決」; centers on how many people or items, not on fullness.
• Related大いにおおいにWrittenWritten/formal adverb meaning greatly or very much, e.g. 「大いに楽しむ」; modifies verbs, not the fullness 「いっぱい」 describes.
• Related多大ただいWrittenWritten/formal. Enormous, as in 「多大な損害」 for losses or contributions; pairs with abstract nouns, far from 「いっぱい」's everyday fullness.
• Related腹いっぱいはらいっぱいCasualColloquial. Eating until you are stuffed, as in 「腹いっぱい食べる」, and by extension doing something to your heart's content; tied to eating, unlike 「いっぱい」.
• Related盛りだくさんもりだくさんNeutralNeutral. Full of rich and varied content, e.g. 「盛りだくさんのイベント」; approving nuance, describing variety rather than a filled container.
• RelatedぎょうさんCasualColloquial Kansai dialect for 'a lot', e.g. 「ぎょうさんある」; can also mean exaggerated or grandiose. Regional, so not a general swap for 「いっぱい」.
• Related万斛ばんこくWrittenWritten/formal and hyperbolic for an immeasurable amount, often seen in 「万斛の涙」; a rhetorical, literary word, nothing like everyday spoken 「いっぱい」.
• RelatedうんとCasualColloquial adverb for a lot or very much, e.g. 「うんと食べる」; a casual, emphatic way to stress large quantity or degree, used much like 「いっぱい」 in speech.
• RelatedしこたまCasualColloquial slang for loads of something, e.g. 「しこたま儲ける」; rough and hyperbolic, suited to casual talk rather than neutral 「いっぱい」.
• RelatedたんとCasualOld-fashioned colloquial for 'plenty', e.g. 「たんとお食べ」; carries an elder's warm tone, a flavor 「いっぱい」 does not have.

For 'full' or 'a lot', 「いっぱい」 is the everyday default. Use 「満杯」 for containers and venues filled to capacity, 「満タン」 for a full tank, and 「ぎゅうぎゅう」 for packed, crowded spaces. For plain quantity choose 「たくさん」, or the more bookish 「多く」. For eating your fill say 「満腹」 or 「腹いっぱい」. The rest are narrower or stylistically marked: mimetic 「パンパン」「きちきち」「きゅうきゅう」「ギチギチ」, loanword 「フル」, rich-content 「盛りだくさん」, formal 「多量」「大いに」「多大」「万斛」, and colloquial 「うんと」「しこたま」「たんと」「仰山」.

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

1. さかずきや茶碗ちゃわんなどの容器ようきに満みちる量りょう。
2. 少すこしの酒さけ。
3. ふねの一いち艘そう。
4. イカやカニの一いち匹ひき。→杯ばい
5. 容器ようき、空間くうかんの限界げんかいまで中身なかみがある状態じょうたい。
6. 限度げんどぎりぎりである様子ようす。余裕よゆうのない様子ようす。
7. (名詞めいしのあとで) ぎりぎり。その最後さいご。終おわるまでの期間きかん。
8. 数多かずおおく。たくさん。