Perspicacity - perspicuity

Listed by Fowler (1931) as a malaprop in the first group: these are two words with similar meanings and origins, which should not be muddled.

• Perspicacity is "insight" (Fowler, 1931), or, more fully, in the OED: "Clearness of understanding or insight; great mental penetration; discernment." The adjective is perspicacious. It derives from the Latin perspcac-, where the ending -ac- or -ax denotes 'having the ability to ...'
• Perspicuity "is clearness or transparency" (Fowler); "In speech, writing, etc.: clearness of statement or exposition; lucidity" (OED, meaning 2). It is derived from the Latin adjective perspicuus, meaning 'clear, evident', and itself derived from spicere 'to see' and per 'through'. The English form is perspicuous.

Fowler points out: -uity of style, -acity of mind", which may serve as a mnemonic for some readers of AWE.