part of a written or typed letter that reaches higher than the top of a letter "x", for example the upper part of the letters "b", "d", or "h"

The point size of a font is measured from the top of the ascender to the bottom of the descender. 字体的磅值是通过测量升部的顶端到降部的底端之间的距离而定的。

His writing was large and flowing, with prominent ascenders and descenders. 他的字大且（线条）流畅，升部和降部都很显眼。

a device that can be attached to a rope and used as a support to hold or stand on when climbing

The final 20 metres to the top was extremely steep, requiring use of the ascender and ice axe to pull you up. 通往山顶的最后20米非常陡峭，需要使用上升器和冰斧来拉着你往上爬。