早く・速く|はやくhayaku[1]atamadaka (head-high)

1. adverb, nounearly; soon
   それが君きみの生活せいかつをよくするのに役立やくだつなら、いくら早はやくとりかかっても早はやすぎることはないよ。↗

   If it is useful for improving your life, it cannot be done too soon.

   あなたが早はやくよくなるように祈いのっています。↗

   We are hoping for your quick recovery.
2. adverbquickly; swiftly; rapidly; fastesp. 速く

• Synonymいち早くいちはやくNeutralStresses being first — acting ahead of everyone else, as in 「いち早く駆けつける」. 「早く」 just says early or fast; this adds the nuance of beating others to it.
• Synonym早々そうそうNeutralAs a suffix it means 'just after ...', as in 「入社早々」; it can also mean doing things hurriedly.
• Synonym早速さっそくNeutralFor getting started on something at once, typically right after receiving news, as in 「早速始める」. It's about diving in without delay rather than being early.
• SynonymさっさとNeutralBriskly, without dallying — and it can carry a cold, dismissive edge, as in 「さっさと帰る」. 「早く」 is neutral and has no such overtone.
• Synonym疾くとくWrittenArchaic written word for swiftly, also 'long ago, already'; rarely seen in modern Japanese.
• Synonym疾く疾くとくとくWrittenArchaic, literary doubling of 「疾く」 meaning 'quickly, swiftly'; carries an old-fashioned air and is very rarely seen today.
• RelatedさっとNeutralA brisk, instantaneous action, or wind and rain arriving suddenly. It homes in on the split-second moment, whereas 「早く」 is the general word for early or fast.
• RelatedみるみるNeutralSomething changing rapidly before your eyes, as in 「見る見る大きくなる」. It highlights the speed of a visible change, not earliness like 「早く」.
• RelatedたちまちNeutralAn instant change — reaching a state in a moment, or something happening all at once. Leans written; 「早く」 is the everyday word for early or fast.
• Related迅速じんそくNeutralA formal noun/na-adjective for swiftness, as in 「迅速な対応」 — prompt handling of a matter. 「早く」 is the plain adverb for everyday use.
• Related至急しきゅうNeutralSignals strong urgency, typical in work messages like 「至急連絡を」. 「早く」 just asks for earliness or speed, without that pressing tone.
• RelatedどんどんNeutralSteady, relentless progress — one thing after another, without hesitation. It stresses continuous momentum, not a single early or fast act like 「早く」.
• RelatedすぐNeutralThe everyday default for 'right away'. 「早く」 stresses being early or moving fast; 「すぐ」 simply says there is no time gap — it happens now.
• RelatedすぐさまNeutralLike 「すぐ」 but more written in flavor, stressing that there is no hesitation at all. 「早く」 remains the neutral everyday choice.
• RelatedパッとNeutralSomething happening in a flash — a quick, snappy motion — and, by extension, standing out showily. It zeroes in on the instant, where 「早く」 is general about speed.
• RelatedちょこちょこNeutralSmall, quick steps or busy little movements; also 'here and there, now and then'. It paints frequent small-scale motion, unlike the overall speed of 「早く」.
• RelatedとっととCasualColloquial 'right now', mostly in impatient commands like 「とっとと帰れ」; brusque and dismissive where 「早く」 is neutral.
• Related大至急だいしきゅうNeutralEven more urgent than 「至急」 — the sooner the better, for when something truly can't wait. 「早く」 is a neutral request for speed.
• Related早いとこはやいとこCasualColloquial for 'quickly, let's get it done', as in 「早いとこ片付けよう」 — casual spoken style, unlike the neutral 「早く」.
• RelatedするするNeutralSmooth, frictionless movement or progress — sliding right along. It stresses how smoothly things go, not earliness or urgency like 「早く」.
• RelatedキリキリNeutralRapid spinning, tightening hard, or gripping pain. It only overlaps with 「早く」 in speed of motion and never means 'early'.
• Related見る間にみるまにNeutralWritten-flavored phrase for something unfolding right before your eyes in an instant. It stresses the visible scene, not the general earliness of 「早く」.
• Related猶予なくゆうよなくWrittenWritten, formal 'without delay', rare in speech — in daily conversation say 「すぐに」. 「早く」 is the neutral everyday word.
• Related直様じきさまNeutralA less common word for 'immediately, on the spot'. In daily speech 「すぐに」 or 「すぐさま」 are the normal choices; 「早く」 is the plain default.
• Antonym遅くおそくNeutralThe antonym: late or slowly — the direct opposite of 「早く」 in both time and speed.

Use 「早く」 for being early or urging someone to hurry, as in 「早く来て」. For 'right away' say 「すぐ」 or 「早速」; to stress being first, 「いち早く」; for urgency, 「至急」 or the stronger 「大至急」. Words like 「見る見る」「パッと」「颯と」 capture instant change or motion; 「とっとと」「早いとこ」 are colloquial; 「疾く」「疾く疾く」 are archaic and 「猶予なく」 written. The opposite is 「遅く」.

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

1. 「はやい」の連用形れんようけい。