1. As the hard flattened scales of e.g. sharks
   - placoid

See also: planar, two-dimensional

• Hooke's law
• hooked
• hooker
• Hooker's green
• Hooker's onion
• Hooker's orchid
• hookey
• hooking
• hooklet
• hooklike
• hooknose
• hooks
• hookup
• hookworm
• hookworm disease
• hooky
• hooky player
• hooligan
• hooliganism
• hoon
• hoop
• hoop ash
• hoop pine
• hoop snake
• hooper