The words leak, leek sound the same but have different meanings and spellings. Why do leak, leek sound the same even though they are completely different words?
The answer is simple: leak, leek are homophones of the English language.
To permit the escape, entry, or passage of something through a breach or flaw: rusted pipes that were beginning to leak; a boat leaking at the seams.
To escape or pass through a breach or flaw: helium leaking slowly from the balloon.
Informal To become publicly known through a breach of secrecy: The news has leaked.
To permit (a substance) to escape or pass through a breach or flaw: a damaged reactor leaking radioactivity into the atmosphere.
An edible plant (Allium porrum) related to the onion and having a white, slender bulb and flat, dark-green leaves.
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.