1. As far as I know

Encyclopedia: AFAIK

• flagellate protozoan
• flagellated
• flagellated cell
• flagellated protozoan
• flagellation
• flagellum
• flageolet
• flagfish
• flagging
• flagitious
• flagman
• flagon
• flagpole
• flagrance
• flagrancy
• flagrant
• flagrantly
• flagroot
• flagship
• flagstaff
• flagstone
• Flagyl
• flail
• flair
• flak