Related Clues:

• Not dull
• Much more than mere
• Very wise
• Smart as a whip
• Extreme, as pain
• Not quite right?
• Very perceptive
• Less than right?
• Like some observations
• Type of triangle
• Shrewd or savvy
• Like angles less than 90 degrees
• Less than 90 degrees, in geometry
• Percipient
• Tough to outwit