The words cete, seat sound the same but have different meanings and spellings. Why do cete, seat sound the same even though they are completely different words?
The answer is simple: cete, seat are homophones of the English language.
A company of badgers. See Synonyms at flock1.
Something, such as a chair or bench, that may be sat on.
A place in which one may sit.
The right to occupy such a place or a ticket indicating this right: got seats for the concert.
The part on which one rests in sitting: a bicycle seat.
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").