pong¹ /pong/ (informal)

To smell bad

A bad smell

• opter
• opters
• optic
• Optic
• optical
• optical activity
• optical art
• optical character reader
• optical character readers
• optical character recognition
• optical computing
• optical disk
• optical disks
• optical-electronic device
• optical-electronic devices
• optical fibre
• optical fibres
• optical illusion
• optical illusions
• optically
• optical maser
• optical masers
• optical microscope
• optical pumping
• optical spectra