Old English sundrian, from sundor "separately, apart," from Proto-Germanic *sunder (cf. Old Norse sundr, Old Frisian sunder, Old High German suntar "aside, apart"), from PIE root *sen(e)- denoting "separation" (cf. Sanskrit sanutar "far away," Avestan hanare "without," Greek ater "without," Latin sine "without," Old Church Slavonic svene "without," Old Irish sain "different"). Related: Sundered; sundering.