sharp as a tack

Idioms and Phrases

Also, sharp as a razor . Mentally acute. For example, She's very witty—she's sharp as a tack . These similes are also used literally to mean “having a keen cutting edge” and have largely replaced the earlier sharp as a needle or thorn . The first dates from about 1900, the variant from the mid-1800s.

Related Words

• able
• active
• deft
• effective
• keen
• ready
• sharp
• vigorous
• wise