必要 bìyào HSK3 necessary Origin Definitions Defs Strokes Stroke Words Sentences Sents 不必要 bùbìyào unnecessary needless; unnecessary必要性 bìyàoxìng necessity 必要条件 bìyàotiáojiàn necessary condition a condition that must be satisfied for a statement to be true or an event to occur in logic or mathematics非必要 fēibìyào unnecessary not required or essential; inessential