The words pair, pare, pear, pere sound the same but have different meanings and spellings. Why do pair, pare, pear, pere sound the same even though they are completely different words?
The answer is simple: pair, pare, pear, pere are homophones of the English language.
Two corresponding persons or items, similar in form or function and matched or associated: a pair of shoes.
One object composed of two joined, similar parts that are dependent upon each other: a pair of pliers.
Two persons who are married, engaged, or dating.
Two persons who have something in common and are considered together: a pair of hunters.
To remove the outer covering or skin of with a knife or similar instrument: pare apples.
To remove by or as if by cutting, clipping, or shaving: pared off the excess dough.
To reduce as if by cutting off outer parts; trim: pare expenses from the monthly budget.
A widely cultivated tree (Pyrus communis) in the rose family, having glossy leaves, white flowers grouped in a corymb, and edible fruit.
The fruit of this tree, spherical at the base and tapering toward the stalk.
Alternative spelling of père.
Definitions from The American Heritage® Dictionary of the English Language, 4th Edition, from Wiktionary, Creative Commons Attribution/Share-Alike License 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").