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.
Archaic To weaken in purpose or spirit.
To fall into a usually brief state of unconsciousness.
An abrupt, usually brief loss of consciousness, generally associated with failure of normal blood circulation. See Synonyms at blackout.
Likely to fall into a faint; dizzy and weak: felt faint for a moment.
To make a deceptive show of.
To deceive with a feint.
To make a feint.
A deceptive action calculated to divert attention from one's real purpose. See Synonyms at wile.
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").