嘘・噓|うそuso[1]atamadaka (head-high)

1. no-adjectivelie; fib; falsehood; untruth
   彼かれが言いったことが嘘うそであることが解わかった。↗

   What he said turned out to be false.
2. no-adjectivemistake; error
3. noununwise move; bad decision
4. interjectionno way!; unbelievable!; really?!
   えっ嘘うそでしょ。↗

   Oh my God, I can't believe this.

• Synonym虚偽きょぎWrittenA Sino-Japanese word for falsehood, common in legal and news contexts, as in 「虚偽の申告」. People don't say 「虚偽をつく」 in everyday speech.
• Synonym偽りいつわりWrittenWritten-style word for falseness and deception, often as a modifier: 「偽りの愛」, 「偽りのない心」. 「嘘」 usually points to a specific lie.
• Synonym虚言きょげんWrittenWritten word for a lie, seen in set phrases like 「虚言癖」; leans medical or formal. In daily conversation people say 「嘘」.
• Synonym嘘偽りうそいつわりWrittenA doubled form used mostly in writing; often with a negative, as in 「嘘偽りのない気持ち」, to stress feelings with no falsehood at all. More formal than 「嘘」.
• Synonym偽ぎNeutralA logic term for a proposition being false, the counterpart of 「真」, as in 「真偽を確かめる」. It does not refer to the act of lying.
• Synonym偽言ぎげんWrittenRare written word for false words; 「嘘」 is the normal choice.
• Synonym虚妄きょもうWrittenVery rare written word for what is false and unfounded, more abstract than 「嘘」; it can also mean embezzlement. Mostly in argumentative prose.
• Synonym妄語もうごWrittenBuddhist term for lying; the five precepts include 「不妄語戒」 against it. Not used for everyday lies.
• Synonym虚辞きょじWrittenWritten word for untrue words; also a grammar term for function words such as particles and auxiliaries. Almost never used for everyday lies.
• Synonym虚語きょごWrittenWritten word for false statements; same meaning as 「虚言」 but even rarer and more obscure.
• Synonym偽り言いつわりごとWrittenAn old-fashioned word for fabricated tales; 「嘘」 has all but replaced it in modern speech.
• Related不実ふじつWrittenMeans dishonesty, unfaithfulness or untruth, as in 「不実な男」; it judges a person's character rather than a single lie.
• Related空言そらごとWrittenA literary, archaic word for falsehoods, also empty promises never acted on. Rare today; say 「嘘」 in daily life.
• Related虚誕きょたんWrittenWritten word for wild, exaggerated talk; stresses absurdity and goes beyond a mere 「嘘」.
• Related詐偽さぎWrittenVery rare written word for falsehood and deceit; don't confuse it with 「詐欺」, fraud. Say 「嘘」 normally.
• Antonym真実しんじつNeutralAntonym of 「嘘」: the truth, as in 「真実を語る」. Somewhat formal.
• Antonym本当ほんとうCasualEveryday antonym of 「嘘」: what is actually true, as in 「嘘か本当か」. Very common in speech.

For an ordinary lie, 「嘘」 is the default. In formal contexts, falsehood is 「虚偽」 (legal, news), while 「偽り」 suits written prose; 「嘘偽りなく」 expresses feelings with no falsehood at all. The opposites are 「本当」 in everyday speech and 「真実」 for truth in a more formal register; the rest are rare or specialized.

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

1. (息いきを) ふく
2. (日本語にほんごのみの用法ようほう) うそ