"public square or open space surrounded by houses," originally in a Spanish or Spanish-American town or city, 1830, from Spanish plaza "square, place," from Vulgar Latin *plattia, from Latin platea "courtyard, broad street" (from PIE root *plat- "to spread").

1650s, "square," with -ic + obsolete quadrate "a square; a group of four things" (late 14c.), from Latin quadratum, noun use of neuter adjective quadratus "square, squared," past participle of quadrare "to square, make square; put in order," related to quadrus "a square," quattuor "four" (from PIE root *kwetwer- "four"). In mathematics by 1660s; the algebraic quadratic equations (1680s) are so called because they involve the square and no higher power of x.

1590s, "open assembly place, chief public square and marketplace of a town; popular political assembly held in such a place," from Greek agora "an assembly of the People" (as opposed to a council of Chiefs); "the place of assembly; a marketplace" (the typical spot for such an assembly), from ageirein "to assemble" (from PIE root *ger- "to gather").

The Greek word also could mean "public speaking," and "things to be sold." For sense, compare Roman forum.

1893, from French escadrille, from Spanish escuadrilla, diminutive of escuadra "square, squad, squadron," from Vulgar Latin *exquadrare, from Latin quadrare "to make square," related to quadrus "a square," quattuor "four" (from PIE root *kwetwer- "four").

"a square-shaped muscle," 1727, from Latin quadratus "square, squared," past participle of quadrare "to square, make square; put in order," related to quadrus "a square," quattuor "four" (from PIE root *kwetwer- "four"). Especially the Quadratus femoris, the muscle situated at the back of the hip-joint.

late 14c., "made square," past-participle adjective from square (v.). Meaning "drawn up in squares" is from 1660s. Of numbers, "multiplied by itself," from 1550s.

1640s, "small number of military men detailed for some purpose," from French esquade, from French escadre, from Spanish escuadra or Italian squadra "battalion," literally "square," from Vulgar Latin *exquadra "to square," from Latin ex "out" (see ex-) + quadrare "make square," from quadrus "a square" (from PIE root *kwetwer- "four"). Before the widespread use of of automatic weapons, infantry troops tended to fight in a square formation to repel cavalry or superior forces. Extended to sports 1902, police work 1905.

"a standard, pattern, or model," 1821 (Coleridge), from French norme, from Latin norma "carpenter's square, rule, pattern," a word of unknown origin. Klein suggests a borrowing (via Etruscan) of Greek gnōmōn "carpenter's square." The Latin form of the word, norma, was used in English in the sense of "carpenter's square" from 1670s, also as the name of a small, faint southern constellation introduced 18c. by La Caille.

"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).

"short, heavy, square-headed, four-edged bolt or arrow for a crossbow," mid-13c., from Old French quarel, carrel "bolt, arrow," from Vulgar Latin *quadrellus, diminutive of Late Latin quadrus (adj.) "square," related to quattuor "four" (from PIE root *kwetwer- "four"). Now-archaic sense of "square or diamond-shaped plane of glass" is recorded from mid-15c., from Medieval Latin quadrellus "a square tile."