1. Off work, but available to provide a service if requested
   "I'm on call for my patients 4 days a week and every fourth weekend"

Encyclopedia: On call

• obtrusiveness
• obtund
• obturate
• obturation
• obturator
• obturator vein
• obtuse
• obtuse angle
• obtuse leaf
• obtuse triangle
• obtuse-angled triangle
• obtusely
• obtuseness
• obverse
• obvert
• obviate
• obviating
• obviation
• obvious
• obviously
• obviousness
• oca
• ocarina
• Occam
• Occam's Razor