The Collaborative International Dictionary of English v.0.48:
Subcommittee \Sub`com*mit"tee\, n. An under committee; a part or division of a committee. [1913 Webster] Yet by their sequestrators and subcommittees abroad . . . those orders were commonly disobeyed. --Milton. [1913 Webster]WordNet (r) 3.0 (2006):
subcommittee n 1: a subset of committee members organized for a specific purpose