What is the name of the pass where Frodo is captured near Mordor?

The pass where Frodo and Sam enter Mordor is called Cirith Ungol. Its name means “Spider’s Cleft” or “Pass of the Spider,” fitting the route’s connection to Shelob’s lair, Torech Ungol.

Cirith Ungol lies in the Mountains of Shadow, north of the more heavily guarded pass by Minas Morgul. Gondor originally built a tower above the route to watch Mordor’s approaches, but by the time of the War of the Ring it has become a dangerous stronghold occupied by Orcs.

Gollum guides Frodo and Sam through the pass, intending to deliver Frodo to Shelob. Shelob attacks Frodo, and Sam believes his master has been killed. After Sam takes the Ring, he discovers Frodo is still alive but has been carried to the Tower of Cirith Ungol, where Orcs capture him. Sam then rescues him.

The wording can cause a small mix-up: Frodo is captured at the tower, rather than literally seized on the mountain pass itself. Cirith Ungol is still the canonical name of the pass and the location associated with that capture.