"arithmetic, music, geometry, astronomy," by 1751, from Latin quadrivium, which meant "place where four roads meet, crossroads," from quadri- "four" (from PIE root *kwetwer- "four") + via "way, road, channel, course" (see via). Compare liberal arts, and also see trivium. The adjective quadrivial is attested from late 15c. in English with the sense "having four roads."
quadrille
quadrillion
quadripartite
quadriplegia
quadriplegic
quadrivium
quadroon
quadru-
quadruped
quadruple
quadruplet