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

Derived forms: retroactions

• lotusland
• Lou Gehrig
• Lou Gehrig's disease
• louche
• loud
• loud pedal
• loud-hailer
• loud-mouthed
• loud-voiced
• louden
• loudly
• loudmouth
• loudness
• loudspeaker
• loudspeaker system
• loufah sponge
• lough
• Louis
• Louis Agassiz
• Louis Antoine de Bougainville
• Louis Aragon
• Louis Armstrong
• Louis Auchincloss
• Louis B. Mayer
• Louis Bleriot