1. 
[syn: slump, slack, drop-off, falloff, falling off]
The Collaborative International Dictionary of English v.0.48:
falloff \falloff\ n.
   a noticeable decline in performance; as, a falloff in
   automobile sales.
   Syn: slump, drop-off, falling off.
        [WordNet 1.5]
WordNet (r) 3.0 (2006):
falloff
    n 1: a noticeable deterioration in performance or quality; "the
         team went into a slump"; "a gradual slack in output"; "a
         drop-off in attendance"; "a falloff in quality" [syn:
         slump, slack, drop-off, falloff, falling off]