I chose 'whisper' as a medium difficulty word because:
1. It's 7 letters long, fitting within the 4-10 letter requirement
2. It contains common letters (w, h, r) mixed with less common ones (p)
3. It's a real English word that most people know, but not one used extremely frequently
4. The 'wh' combination at the start makes it slightly tricky
5. It follows all rules: no spaces, hyphens, or special characters, and uses only a-z letters