N-COUNT [usually poss NOUN] 大伯子；小叔子；内兄；内弟；姐夫；妹夫；连襟 Someone's brother-in-law is the brother of their husband or wife, or the man who is married to their sister. 大伯子；小叔子；内兄；内弟；姐夫；妹夫；连襟