パッとpatto

1. adverbsuddenly; in a flash; quickly; rapidly; swiftly; nimbly
   レース中ちゅうにその車くるまはぱっと燃え上もえあがった。↗

   The car burned up in the race.
2. adverb, suru verbconspicuously; prominently; showily; attractively; impressively

• SynonymさっとNeutralFor quick, crisp actions or sudden wind and rain, as in 「さっと立ち上がる」; it lacks パッと's sense of being conspicuous or spreading all at once.
• SynonymたちまちNeutralFor a state changing in the blink of an eye, as in 「たちまち売り切れる」; stresses how fast the change is, not the crispness or showiness of an action.
• Synonym突然とつぜんNeutralVery common, for things happening with no warning, as in 「突然雨が降る」; stresses the unexpectedness, not パッと's showiness or quickness.
• Synonym突如とつじょWrittenWritten/formal, close to 「突然」 but more solemn, as in 「突如現れる」; common in news reports and narrative prose.
• SynonymにわかにWrittenWritten/formal, for sudden changes like weather, as in 「にわかに曇る」; also for situations changing abruptly. In speech say 「急に」.
• SynonymふとNeutralFor things happening casually or without thinking, as in 「ふと思い出す」; stresses an unconscious thought or move, not speed or showiness.
• SynonymとっさにNeutralFor reacting instantly in an emergency, as in 「咄嗟に避ける」; the point is a split-second response with no time to think, not showiness.
• Synonym不意にふいにNeutralFor catching someone off guard, as in 「不意に声をかけられる」; stresses the other person being unprepared, not crisp action.
• Synonym急にきゅうにNeutralThe most common word in speech, for sudden or sharp changes, as in 「急に寒くなる」; no nuance of being conspicuous or showy.
• Synonym即座にそくざにNeutralFor responding on the spot without hesitation, as in 「即座に答える」; about immediacy, not パッと's showiness.
• SynonymさっさとCasualColloquial, for getting something done briskly, as in 「さっさと帰る」; carries a hurry-up, no-lingering feel and isn't used for natural phenomena.
• SynonymつとWrittenLiterary and old-fashioned, for a sudden quick movement as in 「つと立ち上がる」; it can also mean staying still. In everyday speech say 「さっと」 or 「ふと」.
• SynonymつっとWrittenRare; for moving quickly and smoothly, as in 「つっと前に出る」. 「さっと」 works for everyday use; no sense of being conspicuous.
• SynonymついとWrittenSomewhat literary, for making a move all of a sudden, without warning, as in 「ついと席を立つ」. In daily speech use 「ふいに」 or 「さっと」.
• Synonym忽然こつぜんWrittenWritten/formal, for things suddenly appearing or vanishing, as in 「忽然と姿を消す」; mostly about people or things coming and going.
• Synonym瞬く間にまたたくまにNeutralFor something being done or spreading within the blink of an eye, as in 「瞬く間に広がる」; the point is how short the time is, not watching it happen. Slightly literary.
• SynonymふいとNeutralUncommon, for acting suddenly and without apparent reason, as in 「ふいと出て行く」. In everyday speech say 「ふいに」.
• Synonym一瞬にしていっしゅんにしてWrittenAn adverbial phrase for something happening in an instant, as in 「一瞬にして消える」; it stresses brevity of time even more than パッと and leans written/formal.
• RelatedみるみるNeutralFor watching something change fast before your eyes, as in 「みるみる赤くなる」; it has a sense of process, while パッと is a single instant.
• RelatedとみにWrittenWritten/formal, for marked, rapid changes in degree, as in 「とみに衰える」 or 「とみに有名になる」.
• AntonymじっくりNeutralAntonym: taking time and doing something carefully, as in 「じっくり考える」 — the opposite of パッと's instant, off-the-cuff feel.
• AntonymゆっくりNeutralAntonym: slow and unhurried, as in 「ゆっくり歩く」 — the opposite of パッと's quick, instantaneous action.

Use 「パッと」 for something happening in a flash or standing out, as in 「パッと明るくなる」. For a crisp, quick action say 「さっと」; for sudden events say 「急に」 or 「突然」; for a state changing in no time say 「たちまち」; for something done absent-mindedly say 「ふと」. 「即座に」 and 「咄嗟に」 are about instant responses, 「見る見る」 about change unfolding before your eyes, 「瞬く間に」 about how little time something takes, and 「じっくり」 and 「ゆっくり」 are the opposites. The rest are mostly written or rare variants.

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

1. 瞬時しゅんじに広ひろがるさま。
2. 動作どうさを素早すばやくするさま。なにかが瞬時しゅんじに起おこるさま。
3. 派手はでで目立めだつさま。