informal /in-förˈməl/

1. Not of a formal or conventional nature
2. Characterized by lack of ceremony or formality
3. Relaxed, friendly, unceremonious
4. (esp of clothes) appropriate to everyday or casual use
5. (of speech or writing) having vocabulary, idiom, etc characteristic of conversational speech
6. (of a vote) invalid (Aust and NZ)

informalˈity noun

• prisoners of war
• prison house
• prison houses
• prisoning
• prisonment
• prisonments
• prison officer
• prison officers
• prisonous
• prisons
• prison ship
• prison ships
• prison van
• prison vans
• prison visitor
• prison visitors
• prison yard
• prison yards
• prissier
• prissiest
• prissily
• prissiness
• prissy
• pristane
• pristanes