The words shake, sheik(h) sound the same but have different meanings and spellings. Why do shake, sheik(h) sound the same even though they are completely different words?
The answer is simple: shake, sheik(h) are homophones of the English language.
A fissure in rock.
To cause to move to and fro with jerky movements.
To cause to quiver, tremble, vibrate, or rock.
To cause to lose stability or waver: a crisis that shook my deepest beliefs.
Islam A religious official.
Islam A leader of an Arab family or village.
Islam Used as a form of address for such an official or leader.
Slang A romantically alluring man.
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").