Cite
 

Meaning of subsong

sub•song

Pronunciation: (sub'sông", -song"), [key]
— n.
  1. an unstructured, often rambling vocalization of low volume heard in young birds and, at the start of the breeding season, in adult birds of certain species.
Random House Unabridged Dictionary, Copyright © 1997, by Random House, Inc., on Infoplease.