The 11th king of Gondor (LotR/1038), as well as the name of the father of Eärnil II (LotR/1050). This name seems to be a compound of the river name S. Sirion and the suffix -(n)dil “-friend, -lover”.
Quenya
Siriondil
sirion-friend
siriondil
masculine name. *Sirion-lover
Elements
Word Gloss Sirion “Great River” -(n)dil “-friend, -lover; devotion, disinterested love”
Siriondil masc .name, *"Sirion-friend" (Appendix A)