"extended, stretched out," 1690s, past-participle adjective from now rare or poetic outspread (v.), mid-14c., from out- + spread (v.).
Entries linking to outspread
out-
in Old English a common prefix with nouns, adjectives, adverbs, and verbs, "out, outward, outer; forth, away," from out (adv.). The use was even more common in Middle English, and also with the senses "outer, outside, on the outside, from without, external, externally; apart; greatly, extremely; completely, thoroughly, to completion." Other senses of out that extended into the use as a prefix include "beyond the surface or limits; to the utmost degree; to an explicit resolution."
In composition out has either its ordinary adverbial sense, as in outcast, outcome, outlook, etc., or a prepositional force, as in outdoors, or forms transitive verbs denoting a going beyond or surpassing of the object of the verb, in doing the act expressed by the word to which it is prefixed, as in outrun, outshine, outvenom, etc. In the last use especially out may be used with almost any noun or verb. [Century Dictionary]
spread v.
c. 1200, "to stretch out, to lay out; diffuse, disseminate" (transitive), also "to advance over a wide area" (intransitive); probably from Old English sprædan "to spread, stretch forth, extend" (especially in tosprædan "to spread out," and gesprædung "spreading"), from Proto-Germanic *spreit- (source also of Danish sprede, Old Swedish spreda, Middle Dutch spreiden, Old High German and German spreiten "to spread"), extended form of PIE root *sper- (4) "to strew" (see sprout (v.)).
Reflexive sense of "to be outspread" is from c. 1300; that of "to extend, expand" is attested from mid-14c. Transitive sense of "make (something) wide" is from late 14c. As an adjective from 1510s. Related: Spreading.