"that which has been reduced to a state of purity," 1883, from concentrate(adj.) "reduced to a pure or intense state" (1640s), from concentrate (v.).
Sense of "absolute, utter" (sheer nonsense) developed 1580s, probably from the notion of "unmixed;" that of "very steep" (a sheer cliff) is first recorded 1800, probably from notion of "continued without halting." Meaning "diaphanous" is from 1560s. As an adverb from c. 1600.
"empyreal," mid-14c. (as empyre), probably via Medieval Latin empyreus, from Greek empyros "fiery," from assimilated form of en (see en- (2)) + pyr "fire" (from PIE root *paewr- "fire"). As an adjective in English from early 15c. The etymological sense is "formed of pure fire or light." In ancient Greek cosmology, the highest heaven, the sphere of pure fire; later baptized with a Christian sense of "abode of God and the angels."
"to cause (liquid or granular substance) to flow or stream either out of a vessel or into one," c. 1300, of unknown origin. Not in Old English; perhaps from Old French (Flanders dialect) purer "to sift (grain), pour out (water)," from Latin purare "to purify," from purus "pure" (see pure). Replaced Old English geotan. Intransitive sense of "to flow, issue forth in a stream" is from 1530s. Related: Poured; pouring; pourable. As a noun from 1790, "a pouring stream."