1. Introducing a different topic; in point of fact
   - by the bye, incidentally, apropos

Encyclopedia: By the way

• gray snapper
• gray sole
• gray substance
• gray whale
• gray willow
• gray wolf
• gray-black
• gray-blue
• gray-brown
• gray-green
• gray-haired
• gray-headed
• gray-leaf pine
• gray-pink
• gray-white
• grayback
• graybeard
• grayed
• grayhen
• grayish
• grayish-black
• grayish-blue
• grayish-brown
• grayish-green
• grayish-pink