rhom·bus / ˈrämbəs/ • n. (pl. -bus·es or -bi / -ˌbī; -ˌbē/ ) a parallelogram with opposite equal acute angles, opposite equal obtuse angles, and four equal sides. ∎  any parallelogram with equal sides, including a square.

rhombus

rhombus Plane figure with all of its sides equal in length but no right angles. A rhombus is a type of parallelogram whose diagonals bisect each other at right angles.