Bird’s-mouth

1. n. An interior angle or notch cut across a piece of timber, for the reception of the edge of another, as that in a rafter to be laid on a plate; — commonly called crow’s-foot in the United States.

The word meanings were obtained from OPTED(The Online Plain Text English Dictionary), which is based on “The Project Gutenberg Etext of Webster’s Unabridged Dictionary” which is in turn based on the 1913 US Webster’s Unabridged Dictionary (See Project Gutenburg), as a text file.