Question: what are words with silent letters called?
Answer: inert letters, which are sounded in a cognate word: e.g. 〈n〉 in damn (〈n〉 is pronounced in damnation); 〈g〉 in phlegm (〈g〉 is pronounced phlegmatic); 〈a〉 in practically (〈a〉 is pronounced in practical)