1. Previously unknown
   "developments on an unheard-of scale"

See also: unknown

• UNIX system
• unjoint
• unjointed
• unjust
• unjustifiable
• unjustifiably
• unjustified
• unjustly
• unjustness
• unkempt
• unkemptness
• unkept
• unkeyed
• unkind
• unkind person
• unkindled
• unkindly
• unkindness
• unknot
• unknowable
• unknowing
• unknowingly
• unknowingness
• unknowledgeable
• unknown