elder (n.1)youdaoicibaDictYouDict[elder 词源字典]
"elderly person, senior citizen," c. 1200, from Old English eldra "older person, parent; ancestor; chief, prince" (used in biblical translation for Greek presbyter); see elder (adj.). Compare German Eltern, Danish forældre, Swedish föräldrar "parents." The Old English for "grandfather" was ealdfæder.[elder etymology, elder origin, 英语词源]
nun (n.)youdaoicibaDictYouDict
Old English nunne "nun, vestal, pagan priestess, woman devoted to religious life under vows," from Late Latin nonna "nun, tutor," originally (along with masc. nonnus) a term of address to elderly persons, perhaps from children's speech, reminiscent of nana (compare Sanskrit nona, Persian nana "mother," Greek nanna "aunt," Serbo-Croatian nena "mother," Italian nonna, Welsh nain "grandmother;" see nanny).