The Collaborative International Dictionary of English v.0.48:

Inquietude \In*qui"e*tude\, n. [L. inquietudo: cf. F.
   inquietude.]
   Disturbed state; uneasiness either of body or mind;
   restlessness; disquietude. --Sir H. Wotton.
   [1913 Webster]

WordNet (r) 3.0 (2006):

inquietude
    n 1: feelings of anxiety that make you tense and irritable [syn:
         edginess, uneasiness, inquietude, disquietude]