word-forming element meaning "within, inside, on the inside," from Latin preposition intra "on the inside, within, in, into;" of time, "during, in the course of," related to inter "between," from PIE *en-t(e)ro-, from root *en "in." Commonly opposed to extra-, and compare inter-. The use of intra as a prefix was rare in classical Latin.
1911, from German Gen, coined 1905 by Danish scientist Wilhelm Ludvig Johannsen (1857-1927), from Greek genea "generation, race" (from PIE root *gene- "give birth, beget"). De Vries had earlier called them pangenes. Gene pool is attested from 1946.