1. Operation on something past or preceding 
2. Action returned, or action backward

Derived forms: retroactions

• urban center
• urban centre
• urban guerrilla
• Urban II
• urban legend
• urban planning
• urban renewal
• urban sprawl
• urban typhus
• Urban V
• Urban VI
• Urban VIII
• Urbana
• urbane
• urbanely
• urbanisation
• urbanise
• urbanised
• urbanism
• urbanite
• urbanity
• urbanization
• urbanize
• urbanized
• urceolate