The words erk, irk sound the same but have different meanings and spellings. Why do erk, irk sound the same even though they are completely different words?
The answer is simple: erk, irk are homophones of the English language.
a member of the groundcrew in the RAF.
To be irritating, wearisome, or vexing to. See Synonyms at annoy.
Definitions from Wiktionary, Creative Commons Attribution/Share-Alike License, 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.