いっぺんに・一遍にippenni

1. adverb(all) at once; at the same time; in one go; in one sitting
2. adverbright away; in an instant

• Synonym一度にいちどにNeutralAll at once in a single action; almost interchangeable with 「いっぺんに」, but slightly more formal.
• Synonym一気にいっきにNeutralIn one go without stopping, as in 「一気に飲む」; stresses continuous momentum rather than simultaneity.
• Synonym一時にいちどきにWrittenSimultaneously and all at once; a written/formal-prose word that is little used, close to 「一度に」.
• Related一斉にいっせいにNeutralMany people or things act together, as in 「一斉に拍手」 or 「花が一斉に咲く」; stresses doing things in unison.
• Related同時にどうじにNeutralAt the same time, as in 「同時に始まる」; stresses that things overlap in time.
• Antonym徐々にじょじょにNeutralGradually, steadily; the opposite of 「いっぺんに」 doing everything at once.
• Antonym少しずつすこしずつNeutralLittle by little; the opposite of finishing everything in one go with 「いっぺんに」.

In speech, use 「いっぺんに」 for doing everything at once, as in 「いっぺんに覚えられない」; for a slightly more formal tone use 「一度に」, and for doing something in one go without a break use 「一気に」.

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

1. 全部ぜんぶを一度いちどにすること。同時どうじに行おこなうこと。
2. すぐに。瞬間しゅんかん的てきに。