Fric'tion·al adjective Relating to friction; moved by friction; produced by friction; as, frictional electricity. Frictional gearing , wheels which transmit motion by surface friction instead of teeth. The faces are sometimes made more or less V-shaped to increase or decrease frictio... Found on http://www.encyclo.co.uk/webster/F/76
adjective pertaining to or worked or produced by friction; `frictional electricity`; `frictional heat`; `frictional gearing` Found on https://www.encyclo.co.uk/local/20974