Deltoid

An equation for the deltoid is

(x² + y²)² - 8ax(x² - 3y²) + 18a²(x² + y²) = 27a⁴.

Del"toid (?), a. [Gr. deltoeidh`s delta-shaped; de`lta the name of the letter ei^dos form: cf. F. deltoide. See Delta.]

Shaped like the Greek (delta); delta-shaped; triangular.

Deltoid leaf Bot., a leaf in the form of a triangle with the stem inserted at the middle of the base. -- Deltoid muscle Anat., a triangular muscle in the shoulder which serves to move the arm directly upward.

© Webster 1913.