keen

adjective

1
having a sharp cutting edge or point
a keen blade
2
painful as if caused by a sharp instrument
a cutting wind
keen winds
3
very good
he did a bully job
a neat sports car
4
intense or sharp
suffered exquisite pain
felt exquisite pleasure
5
having or demonstrating ability to recognize or draw fine distinctions
an acute observer of politics and politicians
incisive comments

Also useful for “keen”:Scrabble— High-value letters — see what it scores