What does rhomboid mean?
A rhomboid is a shape resembling a rhombus or diamond: a parallelogram whose four sides are equal and whose opposite angles match, producing pointed ends and slanting sides. The adjective 'rhomboid' is used especially for objects or areas with this outline, though 'diamond-shaped' is often more natural in general speech. In anatomy, the plural 'rhomboids' names two paired muscles beneath the shoulder blades that help move the shoulder blades and support the upper spine. These muscles are commonly shortened to 'rhomboid' when the plural form is intended. The word also has a specialized zoological use for certain bones, notably in birds. Although 'rhombus' is the standard mathematical term for the geometric figure itself, 'rhomboid' remains common in anatomical and specialized descriptive contexts.
Shaped like a rhombus; having four equal sides with parallel opposite sides and pointed ends.
"The crystals formed a series of rhomboid panels."
This use is established but less common than 'diamond-shaped' in general descriptions.
One of the paired muscles of the upper back that connect the shoulder blades to the spinal column.
"The therapist worked slowly to release tension in her rhomboids."
Usually plural; the individual muscles are termed the rhomboid major and rhomboid minor.
A bone shaped like a rhombus, especially one of the bones in the upper back of certain animals.
"The fossil preserves part of the bird's rhomboid."
This is a specialized anatomical or zoological use.
The plural is standard for the paired muscles of the upper back and can also be used for multiple objects or bones of this form.
"Her shoulders rounded forward, tightening the rhomboids."
The rhomboid muscles form a neat diamond beneath the shoulder blades, giving their name both to their shape and to a familiar source of upper-back tension.
Reviewed by Deb Chak, Editor. AI-assisted content curated by RJS Tech Solutions LLP.
Where does rhomboid come from?
The word comes from Greek rhombos, meaning a spinning top or rhombus, combined with the suffix -oeidēs, meaning 'resembling' or 'like.' The form entered English as an adjective describing something shaped like a rhombus and was later applied anatomically to the upper-back muscles. Its relatives include rhomb, rhombus, and rhombic, all belonging to the same Greek family.
Related word forms
How rhomboid is actually used
In geometry, the term is less common than rhombus and is chiefly used attributively. As an anatomical noun, it is usually encountered in the plural 'rhomboids' or in the names 'rhomboid major' and 'rhomboid minor.'
Easily confused with rhomboid
A rhombus is a geometric figure with four equal sides, whereas a rhomboid is something shaped like such a figure.
Rhomboideus is the anatomical term for the paired upper-back muscles commonly called the rhomboids.