1. Of boats, to pull up alongside (abreast) another boat, as when traveling or mooring. We were enjoying the calm of the spring morning, when another boat breasted up and strangers began boarding our ship unannounced.
2. obsolete To cut the face of a plant, especially a hedge, on one side to reveal its stems. Please ask the gardener not to breast up the hedges like that. I know it's meant to promote growth, but I detest the look of the bare stems.
Farlex Dictionary of Idioms. © 2015 Farlex, Inc, all rights reserved.