1. Incapable of being overcome, challenged or refuted
   - impregnable

See also: unconquerable

• rune
• rung
• runic
• runic letter
• runlet
• runnel
• runner
• runner bean
• runner-up
• runner-up finish
• runniness
• running
• running away
• running back
• running blackberry
• running board
• running game
• running hand
• running head
• running headline
• running light
• running mate
• running noose
• running pine
• running play