expansion

1. An increase in size as of chest or lungs. 2. The spreading out of any structure, as a tendon. 3. An expanse; a wide area. [L. ex-pando, pp. -pansus, to spread out]

- clonal e. (klo′nal) production of daughter cells all arising originally from a single cell.

- extensor e. SYN: extensor digital e..

- extensor digital e. a triangular tendinous aponeurosis including the tendon of the extensor digitorum centrally, interosseus tendons on each side, and a lumbrical tendon laterally. It covers the dorsal aspect of the metacarpophalangeal joint and the proximal phalanx. SYN: dorsal hood, extensor aponeurosis, extensor e..

- hygroscopic e. 1. e. due to the absorption of moisture; 2. in dental casting, the addition of water to the surface of the casting investment during setting to increase the size of the mold.

- perceptual e. development of an ability to recognize and interpret sensory stimuli through associations with past similar stimuli; perceptual e. by relaxation of defenses is a goal of psychotherapy.

- setting e. the dimensional increase that occurs concurrently with the hardening of various materials, such as plaster of Paris.

- wax e. in dentistry, a method of expanding wax patterns to compensate for the shrinkage of gold during the casting process.

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ex·pan·sion ik-'span-chən n

1) the act or process of expanding

2) the quality or state of being expanded

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ex·pan·sion (ek-spanґshən) [L. expandere to spread out] 1. the process or state of being increased in extent, surface, or bulk. 2. a region or area of increased bulk or surface. 3. abnormal, excessive occurrence of a triplet repeat.