sulphur dioxide 
(also sulfur dioxide)
noun [mass noun] Chemistry
A colourless pungent toxic gas formed by burning sulphur in air.
- Chemical formula: SO2.
- The District's urban forest improves air quality by removing nitrogen dioxide, sulfur dioxide, carbon monoxide, ozone, and particulate matter.
- When fossil fuels burn, carbon dioxide, sulfur dioxide, nitrogen oxides, sooty particles, dioxins, and other pollutants are released into the air and water.
- crystal
- crystal axis
- crystal ball
- crystal chemistry
- crystal class
- crystal clear
- crystal clock
- crystal-controlled
- crystal cutter
- crystal detector
- crystal diode
- crystal field
- crystal field theory
- crystal form
- crystal-gaze
- crystal gazer
- crystal-gazing
- crystal glass
- crystal globe
- crystal habit
- crystal healing
- crystal lattice
- crystalled
- crystallic
- crystalliferous