/ ˈʃɑːpən; NAmE ˈʃɑːrpən/ verb
1.
to make sth sharper; to become sharper :
[ vn ]
This knife needs sharpening.
[ v ]
The outline of the trees sharpened as it grew lighter.
2.
if a sense or feeling sharpens or sth sharpens it, it becomes stronger and/or clearer :
[ vn ]
The sea air sharpened our appetites.
[also v ]
3.
[ vn ] to make a disagreement between people, or an issue on which people disagree, clearer and more likely to produce a result :
There is a need to sharpen the focus of the discussion.
4.
sharpen (sth) (up) to become or make sth better, more skilful, more effective, etc. than before
SYN improve :
[ v ]
He needs to sharpen up before the Olympic trials.
[ vn ]
She's doing a course to sharpen her business skills.
5.
[ v , vn ] if your voice sharpens or sth sharpens it, it becomes high and loud in an unpleasant way