Meaning

noun the act of breathing heavily through the nose (as when the nose is congested)

verb sniff or smell inquiringly

verb snuff up mucus through the nose

originProbably from Low German and Dutch snuffelen (“to snuffle”), equivalent to snuff + -le. Compare also Old English snofl (“snot, nasal mucus”), which might not have survived into Middle English.

Etymology from Wiktionary, CC BY-SA 3.0