警笛|けいてきkeiteki[0]heiban (flat)

1. nounhorn; alarm; whistle; foghorn

• SynonymホイッスルCasualColloquial loanword for a whistle, most typically the one a referee blows, as in 「試合終了のホイッスル」; 「警笛」 is the word that puts the warning purpose first.
• Synonym呼び子よびこCasualColloquial term for a small whistle used to call out or signal; police, referees and the like carry one.
• Synonym号笛ごうてきWrittenA written/formal-prose term for a whistle blown as a signal; close in sense to 「警笛」 but rarely used.
• Synonym呼笛NeutralNeutral word for a whistle blown to call or contact people; it leans toward summoning rather than warning, so it differs from 「警笛」.
• Synonym呼び笛NeutralNeutral word for a whistle blown to summon or contact someone; it serves a calling purpose, unlike the warning use of 「警笛」.

Use 「警笛」 for a warning horn or whistle from a vehicle, ship or police officer, as in 「警笛を鳴らす」. For a referee's whistle say 「ホイッスル」; for a whistle to call someone, 「呼び子」. 「呼笛」 and 「呼び笛」 are for summoning, while 「号笛」 is a rare written word.

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

1. 警戒けいかいのため笛ふえを鳴ならすこと。また、その笛ふえ。