Old English wid "vast, broad, long," also used of time, from Proto-Germanic *widaz (source also of Old Saxon, Old Frisian wid, Old Norse viðr, Dutch wijd, Old High German wit, German weit), perhaps from PIE *wi-ito-, from root *wi- "apart, away, in half."
Meaning "distended, expanded, spread apart" is from c. 1500; sense of "embracing many subjects" is from 1530s; meaning "missing the intended target" is from 1580s. As a second element in compounds (such as nationwide, worldwide) meaning "extending through the whole of," is is from late Old English. As an adverb, Old English wide. Wide open "unguarded, exposed to attack" (1915) originally was in boxing, etc. Wide awake (adj.) is first recorded 1818; figurative sense of "alert, knowing" is attested from 1833.
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.