Wordnet 3.0
NOUN (1)
1.
a member of the House of Commons who is a minister in the government or who holds an official position in an opposition party;
The Collaborative International Dictionary of English v.0.48:
frontbencher \frontbencher\ n.
a member of the House of Commons of Great Britain who is a
minister or an ex-minister.
[WordNet 1.5]
WordNet (r) 3.0 (2006):
frontbencher
n 1: a member of the House of Commons who is a minister in the
government or who holds an official position in an
opposition party