: a device that protects: such as a (1): a cushion (such as foam rubber or a wood float) between a boat and a dock or between two boats that lessens shock and prevents chafing (2): a pile or a row or cluster of piles placed to protect a dock or bridge pier from damage by ships or floating objects b: railing c: a device in front of locomotives and streetcars to lessen injury to animals or pedestrians in case of collision d: a guard over the wheel of a motor vehicle