countless (adj.)

late 14c., "to enumerate, assign numerals to successively and in order; repeat the numerals in order," also "to reckon among, include," from Old French conter "to count, add up," also "tell a story," from Latin computare "to count, sum up, reckon together," from com "with, together" (see com-) + putare "to reckon," originally "to prune," from PIE root *pau- (2) "to cut, strike, stamp."

Intransitive sense "be of value or worth" is from 1857. Related: Counted; counting. Modern French differentiates compter "to count" and conter "to tell," but they are cognates. To count on "rely or depend upon" is from 1640s. To count against (transitive) "to be to the disadvantage of" is by 1888. To count (someone) in "consider (someone) a participant or supporter" is from 1857; count (someone) out in the opposite sense "leave out of consideration" is from 1854.

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.