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

Encyclopedia: Ad libitum

• Simon Newcomb
• Simon Peter
• Simon the Canaanite
• Simon the Zealot
• Simon Wiesenthal
• Simon Zelotes
• Simon-Pure
• Simone de Beauvoir
• Simone Weil
• simoniac
• Simonise
• Simoniz
• Simonize
• simony
• simoom
• simoon
• simp
• simpatico
• simper
• simperer
• simperingly
• simple
• simple absence
• simple closed curve
• simple eye