indignant (adj.)

1580s, from Latin indignantem (nominative indignans) "impatient, reluctant, indignant," present participle of indignari "to be displeased at, be offended, resent, deem unworthy," from indignus "unworthy," from in- "not, opposite of" (see in- (1)) + dignus "worth (n.), worthy, proper, fitting," from PIE *dek-no-, suffixed form of root *dek- "to take, accept." Related: Indignantly.