The words ternary, turnery sound the same but have different meanings and spellings. Why do ternary, turnery sound the same even though they are completely different words?
The answer is simple: ternary, turnery are homophones of the English language.
Mathematics Involving three variables.
Composed of three or arranged in threes.
Mathematics Having the base three.
A group of three.
The work or workshop of a lathe operator.
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").