Question

make a word that names the thing you have when you explain the meaning of a word.

Explanation:

To form the word for the act of explaining a word's meaning, we combine "define" with the suffix "tion". When adding the suffix, we adjust the spelling of "define" (drop the final 'e' as per common suffix - tion rules for words ending in 'e') to get "definition", which refers to the statement of a word's meaning.

Answer:

definition