1. (idiomatic) in a dangerous, hazardous, or delicate situation; at risk

Encyclopedia: On thin ice

• unmodified
• unmodulated
• unmolested
• unmoor
• unmoral
• unmortgaged
• unmotivated
• unmotorised
• unmotorized
• unmourned
• unmovable
• unmoved
• unmoving
• unmown
• unmuffle
• unmusical
• unmusically
• unmutilated
• unmuzzle
• unmyelinated
• unnameable
• unnamed
• unnatural
• unnaturalised
• unnaturalized