Something that has bothered me forever is that applications that use GNU aspell for spell checking kept marking my name as a misspelling (I’m looking at you, KMail). Most front-end applications don’t provide a way for you to add your own custom words.
If your language is English, create a file in your home directory called “.aspell.en.pws”:
personal_ws-1.1 en 0 Samat quasirhombicosidodecahedron
The first line is a required header. Every subsequent line is a word you want to add to your dictionary. I can’t believe I’ve let this sit for so long. Because it’s a nice text file, syncing this file between machines to take your dictionary with you is trivially easy.