1. disdainful, haughty, conceited, fault-finding; petty, mean ...1871 Amer. sl.
2. having a pleasant or agreeable smell ...1891 Amer. sl.
3. excellent; first-rate ...Bk1942 Amer. sl.
an insignificant person ...1660 Scot. obs.
from snift, (vb.) to sniff
From: The Letters and Journals of Robert Baillie:
Principal of the University of Glasgow,
Edited by David Laing, 1842
For the Earl of Lauderdaill, 12 October, 1660