What is the Gaelic word for Jeremy?

There isn't a direct Gaelic equivalent for the name Jeremy. Gaelic names are typically based on meaning rather than direct translation. To find a Gaelic equivalent, you'd need to consider the meaning of Jeremy (which is usually considered to be from a Hebrew name meaning "exalted by Yahweh"). Then you could choose a Gaelic name with a similar meaning. There are many possibilities depending on the nuance of meaning you'd like to emphasize.