From The Collaborative International Dictionary of English v.0.48 :
Soi-disant \Soi`-di*sant"\ (sw[aum]"d[-e]`z[aum]N"), a. [F.; soi
one's self + disant, p. pr. of dire to say.]
Self-named; self-styled; pretended; would-be.
[Webster 1913 Suppl.]
From WordNet (r) 2.0 :
soi-disant
adj : as claimed by and for yourself often without justification;
"the self-styled `doctor' has no degree of any kind"
[syn: self-styled]