From WordNet (r) 3.0 (2006):
substitute
adj 1: capable of substituting in any of several positions on a
team; "a utility infielder" [syn: utility(a),
substitute(a)]
2: serving or used in place of another; "an alternative plan"
[syn: alternate, alternative, substitute]
3: artificial and inferior; "ersatz coffee"; "substitute coffee"
[syn: ersatz, substitute]
n 1: a person or thing that takes or can take the place of
another [syn: substitute, replacement]
2: an athlete who plays only when a starter on the team is
replaced [syn: substitute, reserve, second-stringer]
3: someone who takes the place of another (as when things get
dangerous or difficult); "the star had a stand-in for
dangerous scenes"; "we need extra employees for summer fill-
ins" [syn: stand-in, substitute, relief, reliever,
backup, backup man, fill-in]
v 1: put in the place of another; switch seemingly equivalent
items; "the con artist replaced the original with a fake
Rembrandt"; "substitute regular milk with fat-free milk";
"synonyms can be interchanged without a changing the
context's meaning" [syn: substitute, replace,
interchange, exchange]
2: be a substitute; "The young teacher had to substitute for the
sick colleague"; "The skim milk substitutes for cream--we are
on a strict diet" [syn: substitute, sub, stand in,
fill in]
3: act as a substitute; "She stood in for the soprano who
suffered from a cold" [syn: substitute, deputize,
deputise, step in]