noun
historicalA festival celebrated (at first annually, later triennially) by the scholars of Eton College, who processed in fancy dress to ‘Salt Hill’, a mound near Slough, to raise money towards the expenses of the senior colleger (called the ‘Captain of the Montem’) when he went up to King's College, Cambridge.
The last procession was held in 1844.
Origin
Mid 18th century. From classical Latin montem (in ad montem to the hill, with reference to a mound near Slough, Berkshire, where the event was held), accusative of mōns mount.
Are You Learning English? Here Are Our Top English Tips