The words cozen, cousin sound the same but have different meanings and spellings. Why do cozen, cousin sound the same even though they are completely different words?
The answer is simple: cozen, cousin are homophones of the English language.
A child of one's aunt or uncle. Also called first cousin.
A relative descended from a common ancestor, such as a grandparent, by two or more steps in a diverging line.
A relative by blood or marriage; a kinsman or kinswoman.
A member of a kindred group or country: our Canadian cousins.
To mislead by means of a petty trick or fraud; deceive.
To persuade or induce to do something by cajoling or wheedling.
To obtain by deceit or persuasion.
To act deceitfully.
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.