A type of letter that's the opposite of a silent letter. A silent letter is seen, but not pronounced. (an example would be the letter G in SIGN) A eyelent letter is pronounced, but not seen. An example word with an eyelent letter would be CELLO, the musical instrument. It's pronounced as if it were written CHELLO, so the letter H is eyelent.
Example word with EYELENT (letter) - cello