Thorin’s sword in J.R.R. Tolkien’s The Hobbit is Orcrist.
Orcrist is an ancient Elvish sword discovered in the troll hoard by Thorin Oakenshield and his companions. The sword’s name is commonly translated as “Goblin-cleaver,” reflecting its history as a weapon used against Orcs and goblins. When the group reaches Rivendell, Elrond identifies the blades and explains their earlier history.
Orcrist was associated with Gondolin, the lost Elven city of the First Age. Its discovery gives Thorin a weapon with a heroic past, but it also makes the sword recognizable to enemies. The Goblins know its reputation, and its presence contributes to the danger surrounding Thorin’s capture in the Misty Mountains.
Orcrist is often mixed up with Glamdring, the sword found in the same troll hoard and later carried by Gandalf. Bilbo’s small sword is Sting. All three blades come from the same episode, but Orcrist belongs specifically to Thorin.