1. Without prior preparation
   - extemporaneously, extempore

See also: extemporary

• unmotivated
• unmotorised
• unmotorized
• unmourned
• unmovable
• unmoved
• unmoving
• unmown
• unmuffle
• unmusical
• unmusically
• unmutilated
• unmuzzle
• unmyelinated
• unnameable
• unnamed
• unnatural
• unnaturalised
• unnaturalized
• unnaturally
• unnaturalness
• unnavigable
• unnecessarily
• unnecessary
• unneeded