Beware, older languages below! The languages below were invented during Tolkien's earlier period and should be used with caution. Remember to never, ever mix words from different languages!

Qenya 

ontare

noun. begetter, parent (f.)

amil

noun. mother

amme

noun. mother

Qenya [Ety/AM¹; PE22/023] Group: Eldamo. Published by

seler

noun. sister

A noun for “sister” in The Etymologies of the 1930s derived from the root ᴹ√THEL or THELES of the same meaning, with an irregular plural selli (Ety/THEL), where the stem form sell- is because the Quenya syncope caused the second e to be lost and then the ancient ls became ll.

Neo-Quenya: In notes from the late 1960s, Tolkien introduced a new word nésa for “sister” (VT47/14). However, I think seler might be retained to mean a “metaphorical” sister, a close female associate who may or may not be related by blood, as with such words as meletheldi “love-sister, ✱close female friend” or ᴹQ. oselle “sworn sister”. In this sense, nésa would be limited to biological relationships, but seler would refer to sisterly (or sister-like) affection.