1. With eyes or mouth open in surprise
   - openmouthed, popeyed

See also: surprised

• flat knot
• flat out
• flat panel display
• flat pea
• flat rate
• flat solid
• flat tip screwdriver
• flat tire
• flat tyre
• flat wash
• flat-bellied
• flat-chested
• flat-coated retriever
• flat-footed
• flat-growing
• flat-hat
• flat-leaf parsley
• flat-pack
• flat-topped
• flat-topped white aster
• flatbed
• flatbed lorry
• flatbed press
• flatbed truck
• flatboat