The Collaborative International Dictionary of English v.0.48:
defuse \de*fuse"\ (d[-e]*f[=u]z"), v. t. [Cf. Diffuse.]
1. To disorder; to make shapeless. [Obs.] --Shak.
2. To remove the fuse from; to deactivate (a bomb or other
explosive device) or make it ineffective.
[WordNet 1.5 +PJC]
3. To make less dangerous; as, to defuse a tense
confrontation between demonstrators and police.
WordNet (r) 3.0 (2006):
v 1: remove the triggering device from [ant: fuse]
Moby Thesaurus II by Grady Ward, 1.0:
18 Moby Thesaurus words for "defuse":
allay, appease, calm, conciliate, cool, dulcify, lay, lay the dust,
mollify, pacify, placate, pour balm on, propitiate, smooth,
smooth down, smooth over, soothe, tranquilize