The words fainted, feinted sound the same but have different meanings and spellings. Why do fainted, feinted sound the same even though they are completely different words?
The answer is simple: fainted, feinted are homophones of the English language.
Lacking strength or vigor; feeble.
Lacking conviction, boldness, or courage; timid.
Lacking brightness: a faint light in the gloom.
Lacking clarity or distinctness: a faint recollection.
A feigned attack designed to draw defensive action away from an intended target.
A deceptive action calculated to divert attention from one's real purpose. See Synonyms at wile.
To make a feint.
To deceive with a feint.
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").