Paleolithic/ˌpali·əʹlithik/ adj

• opal glass
• opaline
• opaque
• op art
• op. cit.
• ope
• OPEC
• open
• open air
• open-air
• open-and-shut
• opencast
• open/cease fire
• open chain
• open circuit
• open-circuit television
• open court
• open day
• open door
• open-ended
• opener
• open-faced
• openhanded
• openhearted
• open-hearth