1. [n]  nasal mucus
2. [n]  a person regarded as arrogant and annoying

SNOT is a 4 letter word that starts with S.

1. \Snot\, n. [AS. snot; akin to D. snot, LG. snotte, Dan.
   snot, and to E. snout. See {Snout}.]
   1. Mucus secreted in, or discharged from, the nose. [Low]
   
   2. A mean, insignificant fellow. [Low]
   
   

2. \Snot\, v. t.
   To blow, wipe, or clear, as the nose.