How to eliminate spell check for only one word?

[Purrcy]

Hello:

I am using the name Autumn in a story, but because autumn is a season (which should not be capitalized) MS Word puts a squiggly blue line under it since I have capitalized it. When I right-click, it only gives me the option to correct one instance of the word at a time, which I have no appetite to do. I have tried to add it to the dictionary, but this has not worked. And, even when I do fix one at a time, as soon as I hit enter or change something, it goes back to having a squiggly underline. How do I fix this so that I can type the name Autumn repeatedly without have MS Word wanting it corrected?

Thank you!