- The climbing of mountains for sport.爬山运动：为运动而爬山
- underclassmen
- underclothes
- underclothing
- undercoat
- undercool
- undercount
- undercover
- undercroft
- undercurrent
- undercurrents
- undercut
- underdeveloped
- underdeveloped
- underdo
- underdog
- underdone
- underdrawers
- underdress
- underdrive
- undereducated
- underemphasize
- underemployed
- underendow
- underendowed
- underestimate