square / frame / rule / (legal) case / style / character / standard / pattern / (grammar) case / (classical) to obstruct / to hinder / (classical) to arrive / to come / (classical) to investigate / to study exhaustively
used in expressions that convey frustration and futility, such as 無奈|无奈[wu2 nai4] and 莫可奈何|莫可奈何[mo4 ke3 nai4 he2] (literary) / used for its phonetic value in writing foreign words