The words wet, whet sound the same but have different meanings and spellings. Why do wet, whet sound the same even though they are completely different words?
The answer is simple: wet, whet are homophones of the English language.
Covered or soaked with a liquid, such as water.
Not yet dry or firm: wet paint.
Stored or preserved in liquid.
Used or prepared with water or other liquids.
To sharpen (a knife, for example); hone.
To make more keen; stimulate: The frying bacon whetted my appetite.
The act of whetting.
Something that whets.
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.