functionless (n.)

1530s, "one's proper work or purpose; power of acting in a specific proper way," from French fonction (16c.) and directly from Latin functionem (nominative functio) "a performance, an execution," noun of action from funct-, past-participle stem of fungi "perform, execute, discharge," from PIE *bhung- "be of use, be used" (source also of Sanskrit bhunjate "to benefit, make benefit, atone," Armenian bowcanem "to feed," Old Irish bongaid "to break, harvest"), which is perhaps related to root *bhrug- "to enjoy." Meaning "official ceremony" is from 1630s, originally in church use. Use in mathematics probably was begun by Leibnitz (1692). In reference to computer operations, 1947.

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.