mural (n.)

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").