From WordNet (r) 3.0 (2006):
invent
v 1: come up with (an idea, plan, explanation, theory, or
principle) after a mental effort; "excogitate a way to
measure the speed of light" [syn: invent, contrive,
devise, excogitate, formulate, forge]
2: make up something artificial or untrue [syn: fabricate,
manufacture, cook up, make up, invent]