aporia /a-pōˈri-a or -pöˈ/

1. A professed doubt of what to say or to choose (rhetoric)
2. A difficulty

• ubiquitary
• ubiquities
• ubiquitin
• ubiquitins
• ubiquitous
• ubiquitously
• ubiquity
• ubi supra
• U-boat
• U-boats
• U-bolt
• U-bolts
• UBR
• ubuntu
• ubuntus
• uc
• UC
• UCAR
• UCAS
• UCATT
• UCCA
• UCI
• uckers
• UCU
• UDA