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

• umbrella
• umbrella arum
• umbrella bird
• umbrella fern
• umbrella magnolia
• umbrella pine
• umbrella plant
• umbrella sedge
• umbrella tent
• umbrella tree
• umbrella-shaped
• umbrellalike
• umbrellawort
• Umbria
• Umbrian
• Umbrina
• Umbrina roncador
• Umbundu
• umiak
• umlaut
• Umma
• Umma Tameer-e-Nau
• Ummah
• ump
• umpirage