1. (of theories etc) incapable of being defended or justified
   - indefensible

See also: unreasonable

• unploughed
• unplowed
• unplug
• unplumbed
• unpointed
• unpointedness
• unpolished
• unpolitical
• unpolled
• unpolluted
• unpompous
• unpopular
• unpopularity
• unpopulated
• unportable
• unposed
• unpotted
• unpowered
• unpractical
• unpracticed
• unpractised
• unprecedented
• unprecedentedly
• unpredictability
• unpredictable