The words wail, wale, whale sound the same but have different meanings and spellings. Why do wail, wale, whale sound the same even though they are completely different words?
The answer is simple: wail, wale, whale are homophones of the English language.
To grieve or protest loudly and bitterly; lament. See Synonyms at cry.
To make a prolonged, high-pitched sound suggestive of a cry: The wind wailed through the trees.
Archaic To lament over; bewail.
A long, loud, high-pitched cry, as of grief or pain.
A mark raised on the skin, as by a whip; a weal or welt.
One of the parallel ribs or ridges in the surface of a fabric such as corduroy.
The texture or weave of such a fabric: a wide wale.
Nautical A gunwale.
Any of various marine mammals of the order Cetacea, having the general shape of a fish with forelimbs modified to form flippers, a tail with horizontal flukes, and one or two blowholes for breathing, especially one of the very large species as distinguished from the smaller dolphins and porpoises.
Informal An impressive example: a whale of a story.
To engage in the hunting of whales.
To strike or hit repeatedly and forcefully; thrash.
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").