1560s, "a chafing, rubbing," from French friction (16c.) and directly from Latin frictionem (nominative frictio) "a rubbing, rubbing down," noun of action from past-participle stem of fricare "to rub, rub down," which is of uncertain origin. Watkins suggests possibly from PIE root *bhreie- "to rub, break." De Vaan suggests a PIE bhriH-o- "to cut" and compares Sanskrit bhrinanti, Old Church Slavonic briti "to shave." Sense of "resistance to motion" is from 1722; figurative sense of "disagreement, clash, lack of harmony, mutual irritation" first recorded 1761. Related: Frictional.

insect excrement, 1854, from German frasz, from root of fressen "to devour, to eat as a beast does" (see fret (v.)).

1590s, "gnawing; disposed to fret," from fret (n.) (see fret (v.)) + -ful. Related: Fretfully; fretfulness.

1878, "without annoyance," from fret (n.) (see fret (v.)) + -less. By 1962 as "without frets" (of a banjo, guitar, etc.), from fret (n.2).

also fret-work, "ornamental work consisting of frets," c. 1600, from fret (n.1) + work (n.).

Proto-Indo-European root meaning "to eat," originally "to bite." 

It forms all or part of: alfalfa; anodyne; comedo; comestible; eat; edacious; edible; escarole; esculent; esurient; etch; ettin; fret (v.); frass; jotun; obese; obesity; ort; postprandial; prandial.

It is the hypothetical source of/evidence for its existence is provided by: Sanskrit admi "I eat;" Avestan ad- "to eat;" Greek edo "I eat;" Latin edere "to eat;" Lithuanian ėdu "I eat," ėdžioti "to devour, bite;" Hittite edmi "I eat," adanna "food;" Armenian utem "I eat;" Old Church Slavonic jasti "to eat," Russian jest "to eat;" Old Irish ithim "I eat;" Gothic itan, Old Swedish and Old English etan, Old High German essan "to eat."  

Proto-Indo-European root forming prepositions, etc., meaning "forward," and, by extension, "in front of, before, first, chief, toward, near, against," etc.

It forms all or part of: afford; approach; appropriate; approve; approximate; barbican; before; deprive; expropriate; far; first; for; for-; fore; fore-; forefather; foremost; former (adj.); forth; frame; frau; fret; Freya; fro; froward; from; furnish; furniture; further; galore; hysteron-proteron; impervious; improbity; impromptu; improve; palfrey; par (prep.); para- (1) "alongside, beyond; altered; contrary; irregular, abnormal;" paradise; pardon; paramount; paramour; parvenu; pellucid; per; per-; percent; percussion; perennial; perestroika; perfect; perfidy; perform; perfume; perfunctory; perhaps; peri-; perish; perjury; permanent; permeate; permit; pernicious; perpendicular; perpetual; perplex; persecute; persevere; perspective; perspire; persuasion; pertain; peruse; pervade; pervert; pierce; portray; postprandial; prae-; Prakrit; pre-; premier; presbyter; Presbyterian; preterite; pride; priest; primal; primary; primate; primavera; prime; primeval; primitive; primo; primogenitor; primogeniture; primordial; primus; prince; principal; principle; prior; pristine; private; privilege; privy; pro (n.2) "a consideration or argument in favor;" pro-; probably; probe; probity; problem; proceed; proclaim; prodigal; produce; profane; profess; profile; profit; profound; profuse; project; promise; prompt; prone; proof; proper; property; propinquity; prophet; prose; prostate; prosthesis; protagonist; Protean; protect; protein; Proterozoic; protest; proto-; protocol; proton; protoplasm; Protozoa; proud; prove; proverb; provide; provoke; prow; prowess; proximate; Purana; purchase; purdah; reciprocal; rapprochement; reproach; reprove; veneer.

It is the hypothetical source of/evidence for its existence is provided by: Sanskrit pari "around, about, through," parah "farther, remote, ulterior," pura "formerly, before," pra- "before, forward, forth;" Avestan pairi- "around," paro "before;" Hittite para "outside of," Greek peri "around, about, near, beyond," pera "across, beyond," paros "before," para "from beside, beyond," pro "before;" Latin pro "before, for, on behalf of, instead of," porro "forward," prae "before," per "through;" Old Church Slavonic pra-dedu "great-grandfather;" Russian pere- "through;" Lithuanian per "through;" Old Irish ire "farther," roar "enough;" Gothic faura "before," Old English fore (prep.) "before, in front of," (adv.) "before, previously," fram "forward, from," feor "to a great distance, long ago;" German vor "before, in front of;" Old Irish air- Gothic fair-, German ver-, Old English fer-, intensive prefixes.