1570s, "a (social) moving, stirring, agitation," from French émotion (16c.), from Old French emouvoir "stir up" (12c.), from Latin emovere "move out, remove, agitate," from assimilated form of ex "out" (see ex-) + movere "to move" (from PIE root *meue- "to push away"). Sense of "strong feeling" is first recorded 1650s; extended to any feeling by 1808.
-less
word-forming element meaning "lacking, cannot be, does not," from Old English -leas, from leas "free (from), devoid (of), false, feigned," from Proto-Germanic *lausaz (cognates: Dutch -loos, German -los "-less," Old Norse lauss "loose, free, vacant, dissolute," Middle Dutch los, German los "loose, free," Gothic laus "empty, vain"), from PIE root *leu- "to loosen, divide, cut apart." Related to loose and lease.