intramural (adj.)

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.

painting on a wall, by 1915, short for mural painting "a painting executed upon the wall of a building" (1850), from mural (adj.) "pertaining to a wall or walls" (mid-15c.), from Latin muralis "of a wall," from murus "wall" (Old Latin moiros, moerus), from PIE *mei- (3) "to fix; to build fences or fortifications" (source also of Old English mære "boundary, border, landmark;" Old Norse -mæri "boundary, border-land;" Latin munire "to fortify, protect").

early 15c., "pertaining to the walls of a cavity in the body," from Late Latin parietalis "of walls," from Latin paries (genitive parietis) "wall" (of a building), a word of unknown origin. In U.S. also "pertaining to the residents and rules of a college or university" (1837; compare intramural). Combining form is parieto-.