There are many words in English language which are not spell the way they sound. Phonetic is one among them.
Phonetic means the representation of the sound of words. It's root word is "phono" which means sound. So to spell it the way it sounds, which would be "fonetik," wouldn't convey the meaning of the word. Most word meanings are recognizable by their roots. This is one such example.
Excellent question. I've never really thought of that. There are so many things in the English language that may raise a ton of questions as to why they exist. Thanks Karim for the information.
