Nantoka/函hán函 (hán) is a Chinese word meaning “envelope; case; letter”.Meanings1envelope2case3letterRelated words邀请函invitation letter函variant of 函[han2]函数function (math.)信函letter函授to teach by correspondence回函a reply (in writing)函馆Hakodate, main port of south Hokkaidō 北海道[Bei3 hai3 dao4], Japan致函to send a letter三角函数trigonometric function函件letters函购mail order公函official letterStudy Chinese with flashcards →