Eluchíl: literally heir of Thingol {1}
Beren and Lúthien came to Ossiriand and as it says in The Silmarillion "dwelt there in Tol Galen the green isle, in the midst of Adurant." Here they bore a son and named him Dior Aranel. {2}
Dior married Nimloth, a relavtive of Celeborn, husband of the Lady Galadriel. {3} Nimloth bore Dior two sons, Eluréd and Elurín, and a daughter, Elwing, who later wedded Eärendil.
The Dwarves of Nogrod came against Menegroth, the Thousand Caves, the underground fortress of Thingol, desiring to steal the Nauglamír, the necklace in which the Silmaril had been set. The dwarves killed Thingol King of Doriath and sacked Menegroth taking the necklace.
Dior fought beside his father, Beren, in the battle with the Dwarves of Nogrod at Sarn Athred. It was in this battle that Beren recovered the Nauglamír. Beren brought the necklace to Lúthien to wear. {4}
After this Dior, together with his family, left his father and mother and settled in Menegroth. Dior pledged to restore the honor and beauty of Doriath. Upon the death of Beren and Lúthien, Dior inherited the Nauglamír. Dior wore the necklace himself. When the sons of Fëanor heard that Dior possessed the necklace, they conspired to assail him and take the Silmaril back. Celegorm lead his brothers against Menegroth. Dior himself slew Celegorm, but he was not to survive. Dior and Nimloth were both murdered in the attack. Dior's sons were abandoned in the woods of Doriath. Only Elwing escaped and she with the Silmaril. {5}
See Also:
Beren and Lúthien | Eluréd and Elurín | The House of Beor
Sources:
1. Index of Names in The Silmarillion
2. The Silmarillion, Chp. 20, p. 229 [1977, pbk]
3. The Silmarillion, Chp. 22, p. 290 [1977, pbk]
4. The Silmarillion, Chp. 22, p. 291 [1977, pbk]
5. The Silmarillion, Chp. 22, p. 291-3 [1977, pbk]
Hypertextual Systems by FMI Publishing, 1995