The words curd, kurd sound the same but have different meanings and spellings. Why do curd, kurd sound the same even though they are completely different words?
The answer is simple: curd, kurd are homophones of the English language.
The part of milk that coagulates when the milk sours or is treated with enzymes. Curd is used to make cheese.
A coagulated liquid that resembles milk curd.
To form or cause to form into curd; curdle.
A member of a pastoral and agricultural people inhabiting the transnational region of Kurdistan in southwest Asia.
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").