From The Collaborative International Dictionary of English v.0.48 [gcide]:
Extortionate \Ex*tor"tion*ate\, a.
Characterized by extortion; oppressive; hard.
[1913 Webster]
From WordNet (r) 3.0 (2006) [wn]:
extortionate
adj 1: greatly exceeding bounds of reason or moderation;
"exorbitant rent"; "extortionate prices"; "spends an
outrageous amount on entertainment"; "usurious interest
rate"; "unconscionable spending" [syn: exorbitant,
extortionate, outrageous, steep, unconscionable,
usurious]