6. Neither of you can use a word that’s been part of a bigger word. So QUIETED will remove QUIET as an option. However, words can share the same stem, so always watch for good words from your opponent and reuse them yourself. -ED, -ISH, -ING(S), -ER(S), -EST, -LY are your friends. (Same for UN-, IN-, RE-, etc, but they’re not as common.)