triple point of a substance is the temperature and pressure at which the three phases (gas, liquid, and solid) of that substance coexist in thermodynamic equilibrium, temperatuur ja rõhk, mille juures aine võib esineda tasakaalus vedelas, tahkes ja gaasilises olekus, kolme olekufaasi tasakaalupunkt, temperature and pressure at which a substance can exist in equilibrium in the liquid, solid, and gaseous states