Deltoid
DELTOID, noun
1. Triangular; an epithet applied to a muscle of the shoulder which moves the arm forwards, upwards and backwards.
2. In botany, shaped somewhat like a delta or rhomb, having four angles, of which the lateral ones are less distant from the base than the others; as a deltoid leaf.
Trowel-shaped, having three angles, of which the terminal one is much further from the base than the lateral ones.