quad

late 14c., "a plane figure having four angles; a rectangle, square, etc.," from Old French quadrangle (13c.) and directly from Late Latin quadrangulum "four-sided figure," noun use of neuter of Latin adjective quadrangulus "having four corners," from Latin quattuor "four" (from PIE root *kwetwer- "four") + angulus "angle" (see angle (n.)). Meaning "four-sided court nearly surrounded by buildings" is from 1590s.

"a blank, low-cast type used by typographers to fill in larger spaces at the end of or between printed lines," 1680s, from French quadrat "a quadrat," literally "a square," from Latin quadratrus, past participle of quadrare "to make square," related to quadrus "a square," quattuor "four" (from PIE root *kwetwer- "four"). Earlier in English it meant a type of surveying instrument with a square plate (c. 1400).