butment

CIDE DICTIONARY

butment, n. [Abbreviation of Abutment.].

A buttress of an arch; the supporter, or that part which joins it to the upright pier. [1913 Webster]
The mass of stone or solid work at the end of a bridge, by which the extreme arches are sustained, or by which the end of a bridge without arches is supported. [1913 Webster]

Butment cheek (Carp.), the part of a mortised timber surrounding the mortise, and against which the shoulders of the tenon bear. Knight.