The words taper, tapir sound the same but have different meanings and spellings. Why do taper, tapir sound the same even though they are completely different words?
The answer is simple: taper, tapir are homophones of the English language.
A small or very slender candle.
A long wax-coated wick used to light candles or gas lamps.
A source of feeble light.
A gradual decrease in thickness or width of an elongated object.
Any of several large, chiefly nocturnal, odd-toed ungulates of the genus Tapirus of tropical America, the Malay Peninsula, and Sumatra, related to the horse and the rhinoceros, and having a heavy body, short legs, and a long, fleshy, flexible upper lip.
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").