Synonyms for Sharpen:

n.

harden, invigorate, confuse, cloud, obscure, stiffen, toughen, clarify, bolster, reinforce, strengthen. chisel, chop, chip away, chase, crimp, drill, sharp, card, acuminate, cut, flail. sharpen (noun)
focalize, point, taper, focus, focalise.

v.

intensify (verb)
increase, strengthen, emphasize, exaggerate, escalate, heighten, magnify, intensify, deepen, stress, underline, accentuate.
make knifelike (verb)
edge, strop, whet, acuminate, sharp, hone, grind, taper, file.
sharpen (verb)
hone, edge.

Other synonyms:

bolster. improve, invigorate, stiffen. toughen, harden. reinforce. edge
strop.
hone
whet.
sharpen
edge.
strap
strop.

Usage examples for sharpen

  1. They sharpen these iron tools upon a coarse slate whetstone, and likewise keep the whole instrument constantly bright. – A General History and Collection of Voyages and Travels, Volume 16 by Robert Kerr
  2. As you so wisely say, let us sharpen our teeth, and pull down all the hay we can get. – Cousin Betty by Honore de Balzac
  3. He knows also the instructions to the corps of papal inquisitors, delivered by Charles and Philip: He knows that Philip, both in person and by letter, had done his utmost to sharpen those instructions, during the latter portion of his sojourn in the Netherlands. – Project Gutenberg History of The Netherlands, 1555-1623, Complete by John Lothrop Motley