ozone: a colorless gas (O3) soluble in alkalis and cold water; a strong oxidizing agent; can be produced by electric discharge in oxygen or by the action of ultraviolet radiation on oxygen in the stratosphere (where it acts as a screen for ultraviolet radiation)
gas: a fluid in the gaseous state having neither independent shape nor volume and being able to expand indefinitely
streptobacillus: any of various rod-shaped Gram-negative bacteria