サインsain

1. noun, suru verb, transitive verb, intransitive verbautograph; signature
   もし彼女かのじょに気付きづいていたら、私はサインをもらっていただろう。↗

   If I had noticed her, I would have got her autograph.
2. noun, suru verb, transitive verb, intransitive verbsign; signal; indication
   あなたはそのサインが消きえるまでタバコを慎つつしむように求もとめられている。↗

   You are asked to refrain from smoking until the sign is switched off.

• Synonym署名しょめいNeutralThe standard term for signing a document, formal in tone, as in 「署名捺印」; 「サイン」 additionally covers a celebrity's autograph.
• Synonym調印ちょういんFormalFormal term for representatives signing and sealing a treaty or agreement, as in 「条約に調印する」.
• SynonymしるしNeutralA mark, sign, or token of something, as in 「感謝の印」; a native word, while 「サイン」 has a strong loanword flavor.
• Synonym合図あいずNeutralA prearranged cue given by gesture or sound, as in 「目で合図する」; close to 「サイン」 in its signal sense.
• Synonym兆しきざしWrittenThe first stirrings of something about to happen, as in 「回復の兆し」; written in flavor.
• Synonym兆候ちょうこうWrittenA sign that has become visible, as in 「病気の兆候」; leans medical and objective.
• SynonymシグネチャNeutralLoanword for a signature or a distinctive personal mark, used mainly in IT and branding, as in 「シグネチャモデル」.
• Synonym書判かきはんWrittenWritten-style term for the signature or written seal placed at the end of a document; an old-fashioned usage.
• Synonym自署じしょWrittenA signature written in one's own hand; used mainly in legal and procedural documents, as in 「自署欄」.
• Related現れあらわれNeutralAn outward expression or manifestation, as in 「愛情の現れ」; matches 「サイン」 only in its indication sense.
• RelatedしるしNeutralA mark, sign, or token of something, as in 「感謝の印」; a native word, while 「サイン」 has a strong loanword flavor.
• Related前兆ぜんちょうNeutralAn omen that something is about to happen, as in 「地震の前兆」; leans toward written style.
• Related気配けはいNeutralA sign felt rather than seen, as in 「春の気配」; stresses an intuitive sense of something nearby.
• Related信号しんごうNeutralAn agreed signal or a traffic light, as in 「信号を送る」 and 「信号が赤だ」.
• Related判はんNeutralA seal or stamp, or a monogram signature, as in 「判を押す」; 「サイン」 is a handwritten signature.
• Related落款らっかんWrittenThe signature and seal an artist puts on a painting or calligraphy work; used only for such artworks.
• Related先触れさきぶれWrittenWritten-style word for advance notice of something, or a portent; little used in modern Japanese.
• Related前表ぜんぴょうWrittenWritten-style word for an omen, or originally a chart presented beforehand; very rare in modern usage.
• Related幸先さいさきNeutralThe sign at the start of an undertaking, usually a good one, as in 「幸先がいい」.
• Related予兆よちょうWrittenA sign that something is about to happen, as in 「不況の予兆」; written in flavor.

「サイン」 covers handwritten signatures and celebrity autographs, secret signals, and signs or indications. For signing a document use 「署名」, for treaty signing 「調印」, for a gestured cue 「合図」, for omens 「兆し」 or 「前兆」, and for an artist's signature and seal 「落款」.

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

1. 署名しょめい。
2. 著名人ちょめいじんが、訪問ほうもんの記念きねんなどにより依頼いらいされて（色紙いろがみ、サイン帳さいんちょうなどに）本人ほんにんに固有こゆうの名前なまえ・文ぶん・記号きごう・図画ずがなどを書かくこと。
3. 合図あいず、信号しんごう。