"disappointed," 1640s, past-participle adjective from frustrate.
Entries linking to frustrated
frustrate v.
"make of no avail, bring to nothing, prevent from taking effect or coming to fulfillment," mid-15c., from Latin frustratus, past participle of frustrari "to deceive, disappoint, make vain," from frustra (adv.) "in vain, in error," which is related to fraus "injury, harm," a word of uncertain origin (see fraud). Related: Frustrated; frustrating.
flustrated adj.
1712, jocular formation from fluster (v.) + frustrated. Related: Flustration.