An Etymological Dictionary of Astronomy and Astrophysics

1. A rectangle having all four sides of equal length.
   
2. The second power of a quantity, expressed as a² = a × a, where a is the quantity. → inverse square law.

Etymology (EN): M.E., from O.Fr. esquire “a square, squareness,” from V.L. *exquadra, from *exquadrare “to square,” from L. → ex- “out” + quadrare “make square,” from quadrus “a square,” from quattuor→ four.

Etymology (PE): Câruš, from Av. caθruša- “four sides (of a four-sided figure)”, from caθru- “four,” Mod.Pers. cahâr, câr “four”

• uša- “angle,” Mod.Pers. guš, gušé.