The Collaborative International Dictionary of English v.0.48:

Arson \Ar"son\ ([aum]r"s'n; 277), n. [OF. arson, arsun, fr. L.
   ardere, arsum, to burn.] (Law)
   The malicious burning of a dwelling house or outhouse of
   another man, which by the common law is felony; the malicious
   and voluntary firing of a building or ship. --Wharton.
   [1913 Webster]

WordNet (r) 3.0 (2006):

arson
    n 1: malicious burning to destroy property; "the British term
         for arson is fire-raising" [syn: arson, incendiarism,
         fire-raising]