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
prairie star: plant with mostly basal leaves and slender open racemes of white or pale pink flowers; prairies and open forest of northwestern United States to British Columbia and Alberta