Spanish word cuadro comes from Proto-Indo-European *kʷétesres, Latin *quadrellus, and later Proto-Italic *kʷettwōr (Four.)
*kʷétesres (Proto-Indo-European)
*quadrellus (Latin)
*kʷetwṓr (Proto-Indo-European)
*kʷettwōr (Proto-Italic)
Four.
quattor (Latin)
(rare, cardinal).
quadrare (Latin)
cuadro (Spanish)
Infield. Painting. Picture. Squad. Square.