Oh English, you're so silly

• Phonetically is spelled phonetically, meaning it is not spelled phonetically. 
• Alliteration contains five syllables, none of which begin with the same sound. 
• The word diphthong doesn't contain any.
• Dactylic isn't. 
• Spondee is a spondee (I think. I'm really bad at meter).

From XKCD

• It's very hard to say the word tooth when you don't have any.
• It's hard to say lisp when you have one.
• The word double-u doesn't contain a w. 
• In Latin, they didn't have the letter w. However, the v was pronounced like w, so which letter did they really not have? 
• A palindrome isn't one.
• Polysyllabic and monosyllabic have the same number of syllables.  

This cartoon illustration has been created by Greg Williams in cooperation with the Wikimedia Foundation.