Definition of "sharpen" [sharp•en]

• To make or become sharp or sharper. (verb-transitive)

American Heritage(R) Dictionary of the English Language, Fifth Edition. Copyright (c) 2011 by Houghton Mifflin Harcourt Publishing Company. Published by Houghton Mifflin Harcourt Publishing Company. All rights reserved.

• "On opposite sides of the country today, the presumptive presidential nominees will once again sharpen their positions on how to manage the conflicts in Iraq and Afghanistan if elected."
• "I asked, feeling my vague dislike for that particular name sharpen up to something dangerously like hatred."
• "I 'sharpen' my hunting knife with a Lansky stone set but I don't with my butcher knives, they're just too long bladed and wear out the stones."