1. Without official authorization
   - on the side 
2. Not in an official capacity
   "unofficially, he serves as the treasurer"

See also: unofficial

Antonym: officially

• Cape Province
• Cape Sable
• Cape Town
• Cape Trafalgar
• Cape tulip
• Cape Verde
• Cape Verde escudo
• Cape Verde Islands
• Cape Verde monetary unit
• cape yellowwood
• Cape York
• Cape York Peninsula
• caped
• Capek
• capelan
• capelin
• capeline bandage
• Capella
• caper
• caper family
• caper sauce
• caper spurge
• caper tree
• capercaillie
• capercailzie