sharp·en 
/ˈʃɑɚpən/ verb
sharp·ens; sharp·ened; sharp·en·ing /ˈʃɑɚpən/ verb 1 [+ obj] : to make (something) sharp or sharper
▪ sharpen a knife/pencil 2 a [+ obj] : to make (something) clearer or more distinct
▪ Can you sharpen the image? ▪ The lecture sharpened my understanding of the topic.
b [no obj] : to become clearer or more distinct
▪ The outlines of the mountains sharpened as we got closer. 3 [+ obj] : to improve (something)
▪ I took a course to sharpen (up) my computer skills. 4 [no obj] : to become more severe
▪ The pain suddenly sharpened.
▪ sharpen a knife/pencil
▪ Can you sharpen the image? ▪ The lecture sharpened my understanding of the topic.
b [no obj] : to become clearer or more distinct
▪ The outlines of the mountains sharpened as we got closer.
▪ I took a course to sharpen (up) my computer skills.
▪ The pain suddenly sharpened.
sharpen up [phrasal verb]
: to become better, smarter, more skillful, etc.
▪ You'd better sharpen up if you want to keep your job.
▪ You'd better sharpen up if you want to keep your job.
