"having unequal sides," 1680s, from Late Latin scalenus, from Greek skalenos "uneven, unequal, rough," from skallein "chop, hoe," related to skelos "leg" (literally "bending") and skolios "crooked," from PIE *(s)kel- "crooked, curved, bent; perverted" (cf. Greek kole "thigh bone," Old Church Slavonic koleno "knee," Lithuanian kelys "knee").