What words have o as a silent letter?

You're asking about words where the letter "o" is silent. This is a little trickier than it sounds! Here's why:

* "Silent" is relative: Some letters are completely silent (like the "e" in "write"), while others are just partially silent (like the "o" in "know").

* Sound changes: The "o" might not be pronounced exactly as in "open," but it could still have a subtle sound.

Here are some examples where "o" is *generally* considered silent:

* "Know" and its derivatives (knowledge, knowing): The "o" is silent, and the word is pronounced as "no."

* "Honest" and "honesty": The "o" is silent, and the word is pronounced as "on-est" and "on-est-ee."

* "Sword": The "o" is silent, and the word is pronounced as "sord."

Examples where "o" has a *subtle* sound:

* "Colonel" and "colonelcy": The "o" has a very short, almost unnoticeable sound, almost like a "uh" sound, but it's not fully silent.

* "Isol(a)te": The "o" is sometimes silent, sometimes pronounced with a very short, unstressed sound.

Important Note: The pronunciation of words can vary between dialects and regions. It's always good to check a dictionary or online resource for the most accurate pronunciation.