1818, "to act as a pontiff," from Medieval Latin pontificatus, past participle of pontificare "to be a pontifex," from Latin pontifex (see pontiff). Meaning "to assume pompous and dignified airs, issue dogmatic decrees" is from 1825. Meaning "to say (something) in a pontifical way" is from 1922. Related: Pontificated; pontificating.
1580s, from Latin pontificatus "office of a pontiff," from pontifex (see pontifex).