pĕr-ācer, ācris, ācre, adj.,
very sharp; trop.: judicium, Cic. Fam. 9, 16, 4 (but in Plaut. Bacch. 3, 3, 1, the correct reading is cor acre; v. Ritschl ad h. l.).
per-ācer ācris, ācre, adj.,very sharp.—Fig.: iudicium. ...
An Elementary Latin Dictionary