From Middle English scharpenen, scharpnen, equivalent to sharp + -en.

• (America) IPA: /ˈʃɑɹpən/
• (RP) IPA: /ˈʃɑːpən/

sharpen (sharpens, present participle sharpening; simple past and past participle sharpened)

1. (transitive, sometimes, figurative) To make sharp.

   to sharpen a pencil or a knife or a musical note

   • 1790 November, Edmund Burke, Reflections on the Revolution in France, and on the Proceedings in Certain Societies in London Relative to that Event. […], London: […] J[ames] Dodsley, […], →OCLC ↗:

     He that wrestles with us strengthens our nerves and sharpens our skill.

2. (intransitive) To become sharp.

• hone (figurative sense)
• whet

• blunt
• blur

• French: affiler, affûter, aiguiser
• German: schärfen (blade), spitzen (pencil)
• Italian: arrotare, affilare, molare, affinare
• Portuguese: afiar (of a blade), apontar (of a point)
• Russian: точи́ть
• Spanish: afilar