Etymology

From Proto-Iranian (compare Persian چهار ‎(chahâr), Kurdish چوار ‎(çwar, çiwar), Avestan čaθwar), from Proto-Indo-Iranian (compare Sanskrit चतुर् ‎(catur)), ultimately from Proto-Indo-European *kʷetwóres (compare Armenian չորս ‎(čʿors), Lithuanian keturi, Latin quattuor English four).