An element in the name Gilthoniel “Star-kindler” which Tolkien explained as “an archaic perfect participle/adjective of √THAN, kindle” in a 1955 letter to David Masson (PE17/82).
Neo-Sindarin: This perfect participle implies the existence of a verb ✱than- “to kindle”, but since Tolkien said the participle was archaic, the verb may be as well, and it is probably better to use attested [N.] nartha- for “kindle” in Neo-Sindarin.
_ v. _archaic perfect participle/adjective. >> Gilthoniel