deltoid

American  

[del-toid] / ˈdɛl tɔɪd /

noun

1. Anatomy. a large, triangular muscle covering the joint of the shoulder, the action of which raises the arm away from the side of the body.

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adjective

1. Anatomy. pertaining to or involving the deltoid.

2. Also in the shape of a Greek capital delta (Δ); triangular.

deltoid British  

/ ˈdɛltɔɪd /

noun

1. the thick muscle forming the rounded contour of the outer edge of the shoulder and acting to raise the arm

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adjective

1. shaped like a Greek capital delta, Δ; triangular

Other Word Forms

• subdeltoid adjective

Etymology

Origin of deltoid

1675–85; < Greek deltoeidḗs delta-shaped, equivalent to délt ( a ) delta + -oeidēs -oid

Explanation

Your deltoid is your shoulder muscle — it makes up the rounded part of your shoulder and allows you to twist, raise, and extend your arms. When deltoid is used as an adjective, it means "triangular," so you could describe your A-frame house or pup tent as deltoid. The deltoid muscle got its name because of its triangular shape and its three distinct sections of muscle fibers. Weight lifters and body builders sometimes call these muscles "delts" for short. Deltoid comes from the Greek deltoeides, "triangular," or "shaped like the Greek letter delta."

Example Sentences

All of the X-Men were strong, their muscles etched from deltoid to abdomen to quadriceps.

From Slate • Jul. 29, 2023

For the second straight day, Servais said he had no updates on the progress of reliever Andres Munoz and his recovery from a right deltoid strain.

From Seattle Times • Apr. 29, 2023

Mariners: LF Sam Haggerty received an MRI, revealing an isolated deltoid strain.

From Washington Times • Aug. 24, 2022

The deltoid tuberosity is a roughened, V-shaped region located on the lateral side in the middle of the humerus shaft.

From Textbooks • Jun. 19, 2013

They would aim for the muscle that Tariq, in a professorial voice, called the deltoid.

From "A Thousand Splendid Suns" by Khaled Hosseini

Related Words

• trilateral