fractious (adj.)

late 14c., originally in the mathematical sense, from Anglo-French fraccioun (Old French fraccion, "a breaking," 12c., Modern French fraction) and directly from Late Latin fractionem (nominative fractio) "a breaking," especially into pieces, in Medieval Latin "a fragment, portion," noun of action from past participle stem of Latin frangere "to break (something) in pieces, shatter, fracture," from Proto-Italic *frang-, from a nasalized variant of PIE root *bhreg- "to break." Meaning "a breaking or dividing" in English is from early 15c.; sense of "broken off piece, fragment," is from c. 1600.

word-forming element making adjectives from nouns, meaning "having, full of, having to do with, doing, inclined to," from Old French -ous, -eux, from Latin -osus (compare -ose (1)). In chemistry, "having a lower valence than forms expressed in -ic."

Proto-Indo-European root meaning "to break."

It forms all or part of: anfractuous; Brabant; bracken; brake (n.1) "stopping device for a wheel;" brake (n.2) "kind of fern;" brash; breach; break; breccia; breeches; brioche; chamfer; defray; diffraction; fractal; fraction; fractious; fracture; fragile; fragility; fragment; frail; frangible; infraction; infringe; irrefragable; irrefrangible; naufragous; ossifrage; refract; refraction; refrain (n.); refrangible; sassafras; saxifrage; suffragan; suffrage.

It is the hypothetical source of/evidence for its existence is provided by: Sanskrit (giri)-bhraj "breaking-forth (out of the mountains);" Latin frangere "to break (something) in pieces, shatter, fracture;" Lithuanian braškėti "crash, crack;" Old Irish braigim "break wind;" Gothic brikan, Old English brecan "to break."