snot n.

early 13c., "trunk or projecting nose of an animal, the nose or jaws when protrusive," not found in Old English, from Middle Low German and Middle Dutch snute "snout," from Proto-Germanic *snut- (source also of German Schnauze, Norwegian snut, Danish snude "snout").

Throughout the Germanic languages a group of words in sn- (Modern German and Yiddish schn-) relate to the human nose or the animal snout. Probably the root is imitative. The senses can extend to the snap of a dog's snout; the snort a horse can make, and the rough or obstructed breathing of a human snore. Also compare snarl, sneeze, snooze, snuff, snoop, snot, etc. Their relation to another Germanic group having to do with "to cut; a detached part" (snip, snick, etc.) is uncertain, but the senses tend to overlap.

Of other animals and (contemptuously) of humans from c. 1300. 16c.-17c. English had snout-fair "good-looking" (1520s).

Lady Strangelove: Not as a suitor to me sir?

Mr. Swaynwit: No you are too great for me. Nor your Mopsey without, though shee be snout-faire, and has some wit shee's too little for me ...

[Brome, "The Court Beggar," 1632]

"to blow or wipe the nose, cast away mucus," c. 1100, sniten, now Scottish and dialectal, from Old English snytan, related to Old Norse snyta, Middle Dutch snuten, Old High German snuzen, German schneuzen "to blow one's nose," and to snot. Nose-sniting "blowing of the nose" is attested from early 15c.