early 15c., "hunt with a ferret," from ferret (n.) or from Old French verb fureter, in reference to the use of half-tame ferrets to kill rats and flush rabbits from burrows. The extended sense of "search out, discover," especially by perseverance and cunning, usually with out (adv.), is from 1570s. Related: Ferreted; ferreting.
late 14c., from Old French furet "ferret," diminutive of fuiron "weasel, ferret," literally "thief" (in allusion to the animal's slyness and craftiness), probably from Late Latin furionem (related to furonem "cat," which also meant "robber"), from Latin fur (genitive furis) "thief," probably from PIE *bhor- (which likely also is the source of furtive), from root *bher- (1) "to bear, carry." Also from the French word are Dutch fret, German Frett. Ferret-faced is from 1837 (to have ferret-eyes is from 1580s).
Proto-Indo-European root meaning "to carry," also "to bear children."
It forms all or part of: Aberdeen; amphora; anaphora; aquifer; auriferous; bairn; barrow (n.1) "frame for carrying a load;" bear (v.); bearing; Berenice; bier; birth; bring; burden (n.1) "a load;" carboniferous; Christopher; chromatophore; circumference; confer; conference; conifer; cumber; cumbersome; defer (v.2) "yield;" differ; difference; differentiate; efferent; esophagus; euphoria; ferret; fertile; Foraminifera; forbear (v.); fossiliferous; furtive; indifferent; infer; Inverness; Lucifer; metaphor; odoriferous; offer; opprobrium; overbear; paraphernalia; periphery; pestiferous; pheromone; phoresy; phosphorus; Porifera; prefer; proffer; proliferation; pyrophoric; refer; reference; semaphore; somniferous; splendiferous; suffer; transfer; vociferate; vociferous.
It is the hypothetical source of/evidence for its existence is provided by: Sanskrit bharati "he carries, brings," bhrtih "a bringing, maintenance;" Avestan baraiti "carries;" Old Persian barantiy "they carry;" Armenian berem "I carry;" Greek pherein "to carry," pherne "dowry;" Latin ferre "to bear, carry," fors (genitive fortis) "chance, luck," perhaps fur "a thief;" Old Irish beru/berim "I catch, I bring forth," beirid "to carry;" Old Welsh beryt "to flow;" Gothic bairan "to carry;" Old English and Old High German beran, Old Norse bera "barrow;" Old Church Slavonic birati "to take;" Russian brat' "to take," bremya "a burden," beremennaya "pregnant."