argon

noun

1. A colourless, odourless gas that makes up about 1% of Earth's air. It is a noble gas and does not react with other substances. Its chemical symbol is Ar.

   C1

   uncountabletechnical

   • "Argon is used inside light bulbs to stop the filament from burning."B2
   • "Welders often use argon to protect hot metal from the oxygen in the air."C1