What is "autoprotolysis"

n. (context chemistry English) The autoionization of water (or similar compounds) in which a proton (hydrogen ion) is transferred to form a cation and an anion e.g. 2H₂O => H₃O⁺ + OH^-

In autoprotolysis a proton is transferred between two identical molecules, one of which acts as a Brønsted acid, releasing a proton which is accepted by the other molecule acting as a Brønsted base. For example, water undergoes autoprotolysis in the self-ionization of water reaction.

Any solvent that contains both acidic hydrogen and lone pairs of electrons to accept H can undergo autoprotolysis.

For example, ammonia in its purest form may undergo autoprotolysis: