1560s, from Latin interspersus "strewn, scattered, sprinkled upon," past participle of *interspergere, from inter- "between" (see inter-) + spargere "to scatter" (see sparse). Related: Interspersed; interspersing.
word-forming element used freely in English, "between, among, during," from Latin inter (prep., adv.) "among, between, betwixt, in the midst of" (also used extensively as a prefix), from PIE *enter "between, among" (source also of Sanskrit antar, Old Persian antar "among, between," Greek entera (plural) "intestines," Old Irish eter, Old Welsh ithr "among, between," Gothic undar, Old English under "under"), a comparative of root *en "in."
A living prefix in English from 15c. and used with Germanic as well as Latinate words. Spelled entre- in French; most words borrowed into English in that form were re-spelled 16c. to conform with Latin except entertain, enterprise. In Latin, spelling shifted to intel- before -l-, hence intelligence, etc.
1727, from Latin sparsus "scattered," past participle of spargere "to scatter, spread, shower," from Proto-Italic *sparg-, from PIE *sp(e)rg- "to strew," extended form of root *sper- "to spread, sow" (source also of Hittite išpar- "to spread out, strew;" Greek speirein "to strew, to sow," spora "a scattering, sowing," sperma "sperm, seed," literally "that which is scattered"). The word is found earlier in English as a verb, "to scatter abroad" (16c.). Related: Sparsely; sparseness.