delta, delt-; Δ, δ

The pattern of slow waves (delta waves) of an electroencephalogram, having a frequency of less than 3.5 per second, and typically occurring during deep sleep, in infancy, and in serious brain disorders.

A mathematical expression for a change in velocity; especially, referring to spacecraft: Delta V designates the speed changes required to transfer a spacecraft from one orbit to another one.

One of the high-amplitude, slow, and regular brain waves that characterize the stages of deep sleep: The delta waves are "deep-sleep waves" that are associated with a dreamless state from which an individual is not easily aroused.

A triangular, swept-back aircraft wing that provides speed and lift: A delta wing has a low aspect ratio, a sharply tapered leading edge, a straight trailing edge, and a pointed tip.

Relating to, or like, a deposit of fine alluvial sediments (sand, earth, and other minerals) at the mouth of a river.

A sedimentary deposit consisting of a mixture of sand, clay, and organic matter laid down in a delta.

Descriptive of a land formation at the mouth of a river which has been created by deposits of sediments: Some deltic areas consist of mud and sand carried by flowing water into ponds, lakes, or parts of rivers.

Someone who collects post cards. There is no connection to the "deltic muscle".

The collection and study of postcards: Deltiology has no reference to the deltic muscle. It comes from Greek deltion, "little writing tablet" and it comes from Greek deltos, "writing tablet"; so, it is presented so you will know that it has nothing to do with the other words in this delta unit.

1. In the shape of the fourth letter of the Greek alphabet: A capitalized delta is a triangle; so, deltoid means triangular in shape or configuration.
2. The large muscle, roughly triangular in shape, that stretches from the clavicle (collarbone) to the humerus (the long bone in the upper arm) and so covers the shoulder: When a deltoid is contracted (flexed), it moves an arm away from the side of the body.

The central, strongest part of the deltoid muscle, raises an arm sideways while the front and back parts of the muscle can twist the arm.

The internal lateral or medial ligament of the ankle joint.

A large, thick triangular muscle that covers the shoulder joint: The deltoid muscle is the prime mover of the arm away from the central turning part of the body and it is also a synergist (working in combination with something else to increase its activity) of arm flexion (process of bending or the state of being bent), extension, and medial and lateral rotations.

The ridge on the humerus where the deltoid muscle is attached.

The shape of a Greek capital delta (Δ); triangular.

A reference to a large, thick triangular muscle which covers the shoulder joint: The deltoideus muscles are the primary movers of arm flexions, extensions, and medial and lateral rotations.