1. Concave on both sides
   - concavo-concave

See also: concave

• humic shale
• humic substance
• humid
• humidex
• humidifier
• humidify
• humidity
• humidly
• humidness
• humidor
• humification
• humified
• humify
• humiliate
• humiliated
• humiliating
• humiliatingly
• humiliation
• humility
• humin
• hummer
• humming
• humming bird's trumpet
• humming top
• hummingbird