The words sighs , size sound the same but have different meanings and spellings. Why do sighs , size sound the same even though they are completely different words?
The answer is simple: sighs , size are homophones of the English language.
To exhale audibly in a long deep breath, as in weariness or relief.
To emit a similar sound: willows sighing in the wind.
To feel longing or grief; yearn: sighing for their lost youth.
To express with or as if with an audible exhalation.
The physical dimensions, proportions, magnitude, or extent of an object.
Any of a series of graduated categories of dimension whereby manufactured articles, such as shoes and clothing, are classified.
Considerable extent, amount, or dimensions: a debt of enormous size.
Relative amount or number, as of population or contents: What size is Cleveland?
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.