Merriam-Webster's Collegiate® Dictionary, 11th Edition
FRUSTRATE
I. transitive verb (frustrated; frustrating)
Etymology: Middle English, from Latin frustratus, past participle of frustrare to deceive, frustrate, from frustra in error, in vain
Date: 15th century
1. to balk or defeat in an endeavor, to induce feelings of discouragement in,
2. a. to make ineffectual ; bring to nothing, impede , obstruct , to make invalid or of no effect, Synonyms: see: frustrate
II. adjective
Date: 15th century
characterized by frustration