invincible

adj. 不可征服的，难以制服的

investigate, investigation, investigative, investigator, investiture, investment, investor, inveterate, inveterately, invidious, invidiously, invidiousness, invigilate, invigilation, invigilator, invigorate, invigorating, invigoratingly, invigoration, invincibility, invincibly, inviolability, inviolable, inviolably, inviolate, invisibility, invisible, invisible ink, invisible mending, invisibly, invitation, invite, invite sb. to (sth.,a place), inviting, invitingly, invocation, invoice, invoke, involuntarily, involuntariness,