English Vocabulary Flash Cards @ englishpdf.com and englishteststore.com File 322 inveterate (adj) Habitual invidious (adj) Showing or feeling envy invigorate (v) To animate invincible (adj) Not to be conquered, subdued, or overcome inviolable (adj) Incapable of being injured or disturbed invoke (v) To call on for assistance or protection involuntary (adj) Unwilling involution (n) Complication