- Either of two angles formed by two intersecting lines and lying on opposite sides of the point of intersection.对顶角：由两条相交线形成的两个角，它们分别处在相交点的两边
- unit
- Unit.
- unitard
- unitards
- Unitarian
- Unitarian Universalism
- unitary
- Unitas
- unit cell
- unit character
- unit cost
- unite
- united
- united
- United Arab Emirates
- United Arab Republic
- United Electronics Institute
- United Kingdom
- United Nations
- United States
- United States Air Force Academy
- United States Coast Guard Academy
- United States International University
- United States Merchant Marine Academy
- United States Military Academy