Hísimë, meaning 'Misty', was the Quenya name of the eleventh month of the year according to the Númenórean calendar (Steward's Reckoning in Gondor). It was the equivalent of our modern day November, running from 22 October through 20 November.

Hithui was the Sindarin equivalent, but it was only used by the Dúnedain.
Encyclopedia entry originally written by ~Venora~