Related Clues:

• Less than 90 degrees
• Like some triangle angles
• Acutely sensitive
• Sharp or severe
• Quite sharp, as a pain
• Observant
• Well-tuned
• Angle less than 90 degrees
• Very serious
• On the bright side
• Type of angle
• Incisive
• Sharp, as vision
• Sagacious
• Sharply focused