Pronunciation: (del'toid), [key]
Anat.a large, triangular muscle covering the joint of the shoulder, the action of which raises the arm away from the side of the body.
1. Anat.pertaining to or involving the deltoid.
2. Also,deltoidal.in the shape of a Greek capital delta (Δ); triangular.
Random House Unabridged Dictionary, Copyright © 1997, by Random House, Inc., on Infoplease.