出典:Wiktionary
From Middle English warnen, warnien (“to warn; admonish”), from 古期英語 warnian (“to take heed; warn”), from Proto-Germanic *warnōną (“to warn; take heed”), from Proto-Indo-European *wer- (“to be aware; give heed”). Cognate with Dutch waarnen (廃れた用法), German Low German warnen, German warnen, Swedish varna, Icelandic varna.
warn (三人称単数 現在形 warns, 現在分詞 warning, 過去形および過去分詞形 warned)