furo.

Uncertain. * Possibly cognate with Proto-Slavic *buřa (cf. Russian буря (burja, “storm”)) and Sanskrit भुरति (bhurati, “to palpitate, quiver”), which would point to Proto-Indo-European *bʰur-. * Perhaps derived from *dʰewh₂- (“to smoke”) * The LIV suggests the term may derive from an athematic root present of *bʰerh₂-, perhaps whence also Hittite [script needed] (parḫ-ᶻⁱ). * Kroonen suggests that the term may derive from Proto-Indo-European *dʰus-e-, itself from the root *dʰwes- (“to breathe, exhale”), in which case it would connect with Proto-Germanic *dusāną (“to slumber”). Regarding the sense development, Kroonen suggests that the Proto-Indo-Europeans perhaps believed that the soul left the body during sleep, whence meanings such as “to lose one’s senses” and “to go mad.” De Vaan, however, finds no proposed etymology for this verb convincing. According to De Vaan, Proto-Italic *u is expected to yield Latin o in front of *-rV- sequences, therby excluding any Proto-Indo-European preform including *-us- or *-ur-.

Etymology tree Proto-Indo-European *bʰer- Proto-Indo-European *-s Proto-Indo-European *bʰṓr Proto-Italic *fōr Latin fūr Proto-Indo-European *-h₂ Proto-Indo-European *-éh₂ Proto-Indo-European *-yéti Proto-Indo-European *-eh₂yéti Proto-Indo-European *-h₂tiinflu. Proto-Italic *-ājō Proto-Italic *-āō Latin -or Latin fūror Proto-Indo-European *-ōder. Proto-Indo-European *-Hōder.? Latin -ō Latin fūrō From fūror (“to steal”) + -ō.