The name of tengwa #36 [.] in The Lord of the Rings Appendix E (LotR/1123), a derivative of √UR “heat” (PE22/160). This name probably reflects its use for u-diphthongs in Tengwar spelling.
Conceptual Development: In the 1st edition of The Lord of the Rings the name of tengwa #36 was úr “heat” (RC/736), and in earlier documents on The Feanorian Alphabet this word was glossed “fire, heat” (PE22/51) or just “fire” (PE22/23); see the discussion under ᴹQ. úr for further details.