The words wack(s), whack(s), wax sound the same but have different meanings and spellings. Why do wack(s), whack(s), wax sound the same even though they are completely different words?
The answer is simple: wack(s), whack(s), wax are homophones of the English language.
A person regarded as eccentric.
Very bad: walked out of a really wack movie.
Any of various natural, oily or greasy heat-sensitive substances, consisting of hydrocarbons or esters of fatty acids that are insoluble in water but soluble in nonpolar organic solvents.
A solid plastic or pliable liquid substance, such as ozocerite or paraffin, originating from petroleum and found in rock layers and used in paper coating, as insulation, in crayons, and often in medicinal preparations.
To strike (someone or something) with a sharp blow; slap.
Slang To kill deliberately; murder.
To deal a sharp, resounding blow.
A sharp, swift blow.
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.