What is called when you add a y to the end of word?

There isn't a specific term for adding a "y" to the end of a word. It's generally considered part of word formation or morphology.

Here are some possible scenarios where you might add a "y" to a word:

* Pluralizing nouns: Some nouns, usually ending in "-ies," are pluralized by adding a "y" (e.g., "baby" becomes "babies").

* Creating adjectives: Some adjectives are formed by adding a "y" to a noun (e.g., "cloud" becomes "cloudy").

* Creating adverbs: Some adverbs are formed by adding a "y" to an adjective (e.g., "happy" becomes "happily").

* Informal language: In some informal contexts, a "y" might be added to a word for emphasis or humor, but this is not considered standard grammar (e.g., "happy" becomes "happy-y").

If you can provide more context about the specific word and how you're adding a "y," I might be able to give you a more precise answer.