1. Without advance preparation
   - ad lib, spontaneously, impromptu

Encyclopedia: Ad libitum

• areolar
• areolar tissue
• areolate
• Areopagite
• Areopagus
• Arequipa
• arere
• Ares
• areteria cervicalis
• arethusa
• Arethusa bulbosa
• argal
• argali
• argasid
• Argasidae
• argemone
• Argemone mexicana
• argent
• argentic
• argentiferous
• Argentina
• argentine
• Argentine hemorrhagic fever
• Argentine monetary unit
• Argentine Republic