The Collaborative International Dictionary of English v.0.48:
defusing \defusing\ (d[-e]*f[=u]z"[i^]ng), n. 1. The act of deactivating or making ineffective (as a bomb). Syn: deactivation. [WordNet 1.5]WordNet (r) 3.0 (2006):
defusing n 1: the act of deactivating or making ineffective (as a bomb) [syn: deactivation, defusing] [ant: activation]