- universal validity
- universal variety
- universal λ-ring
- universe
- universe mean
- universe of a structure
- universe of discourse
- univocacy
- univocal
- uni-【前缀】
- unknot
- unknotted
- unknotted curve
- unknotted knot
- unknottedness
- unknotted solid tube
- unknotting
- unknotting conjecture
- unknotting number
- unknotting theorem
- unknown
- unknown function
- unknown number
- unknown parameter
- unknown quantity