1. Not knowledgeable about something specified
   "a person unacquainted with our customs"
   - innocent 
2. Having little or no knowledge of
   "unacquainted with city ways"
   - unacquainted with, unfamiliar with

See also: unfamiliar, uninformed

• factory worker
• factory-made
• factotum
• facts of life
• factual
• factuality
• factually
• factualness
• factum
• facture
• facula
• facultative
• faculty
• faculty member
• fad
• fad diet
• faddily
• faddish
• faddishly
• faddist
• faddy
• fade
• fade away
• faded
• fadeless