Words don't really die out they just drop out of common usage or change in meaning. There are a significant number of words that have fallen out of common usage. "perchance" for example or "sitten" which is a no longer used tense of sat example usage "we had sitten". Thee and thou the now archaic forms of the personal pronoun you and thine the archaic form of the possessive pronoun your. However all of these although no longer in common usage are still used so technically they haven't died out. Well except perhaps sitten. Is there something specific you are looking for? you can just look for old English or middle English is you want more examples. Those are however almost different languages.

die out means go extinct. If we don't take care this species will die out. If we don't take care this species will go extinct.

"Victrola" (for a phonograph or record player) "bankbook" "icebox" "senility" (do not ask me what the difference is between "senility" and "dementia!") "catarrh" "neurasthenia" "score" (for the number 20) "gross" (for the number 144) "semiquaver" (for a 1/16th note in music) "charisma" (became common in the 1970s and 1980s and then became rare again) "demijohn" "hogshead," "furlong," "rod," "dram," "gramme"--outdated units of weight and measure