The words sac, sack, sacque sound the same but have different meanings and spellings. Why do sac, sack, sacque sound the same even though they are completely different words?
The answer is simple: sac, sack, sacque are homophones of the English language.
A pouch or pouchlike structure in a plant or an animal, sometimes filled with fluid.
A large bag of strong coarse material for holding objects in bulk.
A similar container of paper or plastic.
The amount that such a container can hold.
A short loose-fitting garment for women and children.
Variant of sack1.
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.