Derived from Latin 'quadra' (a square) via Old French, ultimately from the Proto-Indo-European word for 'four' — literally a shape 'made into a four.'
A plane figure with four equal straight sides and four right angles; an open area at the meeting of streets; an L-shaped or T-shaped instrument for testing right angles.
From Old French esquarre (a carpenter s square), from Vulgar Latin *exquadra, a compound of Latin ex- (out) + quadrare (to make square). Quadrare derives from quadrus (square, four-sided), which comes from Proto-Indo-European *kʷetwóres (four) via Latin quattuor. The PIE numeral root *kʷetwóres is one of the most widely attested in the family: Greek téssares, Sanskrit catvāri, Old Irish cethair, Welsh pedwar. The geometric sense — a right
The words 'square,' 'quarter,' 'quarantine,' and 'squad' all descend from the Latin word for 'four.' A squad was originally a group of soldiers arranged in a square formation, and quarantine was originally a 40-day (four-tens) period of isolation for ships arriving in Venice during plague outbreaks.