rhomboid

American Heritage® Dictionary of the English Language, Fourth Edition

1. n. A parallelogram with unequal adjacent sides.
2. adj. Shaped like a rhombus or rhomboid.

Century Dictionary and Cyclopedia

1. Having a form like or approaching that of a rhomb; having the shape of a rhomboid (see II., 1); rhomboidal. Specifically— In anatomy, rhombiform, as a muscle or ligament; pertaining to the rhomboidei or rhomboideum.
2. n. In geometry, a quadrilateral figure whose opposite sides and angles are equal, but which is neither equilateral nor equiangular; a non-equilateral oblique parallelogram.
3. n. In crystallography, a solid having a rhomboidal form with three axes of unequal lengths, two of which are at right angles to each other, while the third is so inclined as to be perpendicular to one of the two axes, and oblique to the other.
4. n. In anatomy, a rhomboideus.
5. n. In anthropology, a cranium the norma verticalis of which has a rhomboid form.

Wiktionary

1. n. A parallelogram which is neither a rhombus nor a rectangle
2. n. Any of several muscles that control the shoulders
3. n. A solid shape which has rhombic faces
4. adj. resembling, or shaped like a rhombus or rhomboid

GNU Webster's 1913

1. n. (Geom.) An oblique-angled parallelogram like a rhomb, but having only the opposite sides equal, the length and with being different.
2. adj. Same as rhomboidal.

WordNet 3.0

1. n. any of several muscles of the upper back that help move the shoulder blade
2. n. a parallelogram with adjacent sides of unequal lengths; an oblique-angled parallelogram with only the opposite sides equal
3. adj. shaped like a rhombus or rhomboid