Oprindelseis (“ice”) + tid (“time”)
Formeristiden(definite, singular) · istider(indefinite, plural) · istid(indefinite, nominative, singular) · istiden(definite, nominative, singular) · istider(indefinite, nominative, plural) · istiderne(definite, nominative, plural) · istids(genitive, indefinite, singular) · istidens(definite, genitive, singular) · istiders(genitive, indefinite, plural) · istidernes(definite, genitive, plural)