Nouns

(n)rhomboida parallelogram with adjacent sides of unequal lengths; an oblique-angled parallelogram with only the opposite sides equal
(n)rhomboid, rhomboid muscleany of several muscles of the upper back that help move the shoulder blade

Adjectives

(a)rhomboid, rhomboidalshaped like a rhombus or rhomboid“rhomboidal shapes”