The words ex, x sound the same but have different meanings and spellings. Why do ex, x sound the same even though they are completely different words?
The answer is simple: ex, x are homophones of the English language.
Not including; without: a stock price ex dividend.
Business Free of any transport or handling charges incurred before removal from a given location: bought the goods ex warehouse.
From, but not having graduated with, the class of: a Columbia alumnus, ex '70.
The letter x.
The 24th letter of the modern English alphabet.
Any of the speech sounds represented by the letter x.
The 24th in a series.
Something shaped like the letter X.
Definitions from The American Heritage® Dictionary of the English Language, 4th Edition and Wordnik.
Homophones (literally "same sound") are usually defined as words that share the same pronunciation, regardless of how they are spelled.
If they are spelled the same then they are also homographs (and homonyms); if they are spelled differently then they are also heterographs (literally "different writing").