A small [island], especially in the Thames.
You say it like the number eight. Anyone living along the River Thames upstream of London as far as about Windsor or Reading will know this word, as it’s commonly used in the names of the little islands that dot the river in those reaches. But for most [British] people it surfaces only as a curious term during commentaries on the Oxford-Cambridge boat race, when places like Chiswick Eyot are regularly mentioned. It’s from Old English iggath (or igeth), which is based on ieg, an island, plus a diminutive suffix. So—a small island. As you might expect from its Old English credentials, it turns up in a couple of places in J R R Tolkien’s Lord of the Rings: “That night they camped on a small eyot close to the western bank”. An older form that’s more obviously connected to the way you say it is ait, a spelling retained in the names of some of the Thames islands and which Charles Dickens used in Bleak House: “Fog everywhere. Fog up the river, where it flows among green aits and meadows; fog down the river, where it rolls deified among the tiers of shipping and the waterside pollutions of a great (and [dirty]) city”.
