Collins English Dictionary states that this word is ultimately derived from Middle Dutch loef. Ellert Ekwall's Shakspere's Vocabulary: its etymological elements (1903) related this verb and loof instead to the East Frisian verb lofen, lufen, which would make it cognate to the French term lover.
luff (plural luffs)
- (nautical) The vertical edge of a sail that is closest to the direction of the wind.
- (nautical, of a sail, intransitive) To shake due to being trimmed improperly.
- (nautical, of a boat, intransitive) To alter course to windward so that the sails luff. (Alternatively luff up)
- (nautical, transitive) to let out [a sail] so that it luffs.
- (mechanical) To alter the vertical angle of the jib of a crane so as to bring it level with the load.