What is the meaning of volatile?

noun

• A volatile substance; a substance that changes readily from solid or liquid to a vapor.
  • usage: "it was heated to evaporate the volatiles"

adjective

• Evaporating readily at normal temperatures and pressures.
  • usage: "volatile oils"; "volatile solvents"
• Liable to lead to sudden change or violence.
  • usage: "an explosive issue"; "a volatile situation with troops and rioters eager for a confrontation"
  • synonyms: explosive
• Marked by erratic changeableness in affections or attachments.
  • usage: "fickle friends"; "a flirt's volatile affections"
  • synonyms: fickle
• Tending to vary often or widely.
  • usage: "volatile stocks"; "volatile emotions"