Wordnet 3.0
VERB (2)
1. 
 end weakly; 
- Example: "The music just petered out--there was no proper ending"[syn: taper off, peter out, fizzle out, fizzle]
2.  become smaller or less active; 
- Example: "Business tapered off"
WordNet (r) 3.0 (2006):
taper off
    v 1: end weakly; "The music just petered out--there was no
         proper ending" [syn: taper off, peter out, fizzle
         out, fizzle]
    2: become smaller or less active; "Business tapered off"