The words missable, miscible sound the same but have different meanings and spellings. Why do missable, miscible sound the same even though they are completely different words?
The answer is simple: missable, miscible are homophones of the English language.
Chemistry That can be mixed in all proportions. Used of liquids.
Able to avoid detection.
Far from unmissable; not worth watching or experiencing.
Capable of being missed.
Definitions from The American Heritage® Dictionary of the English Language, 4th Edition, from Wiktionary, Creative Commons Attribution/Share-Alike License and Wordnik.
Homophones (literally "same sound") are usually defined as words that share the same pronunciation, regardless of how they are spelled.