Late 17th century (denoting an early Christian bishop): from French pontife, from Latin pontifex (see pontifex).
Referring to the pope, this word is from French pontife, from Latin pontifex meaning literally ‘bridge-maker’ but used in ancient Rome as a term for a member of the principal college of priests. This also gives us pontificate (Late Middle English). The use ‘express opinions in a pompous way’ dates from the early 19th century. The same pont- ‘bridge’ element is found in pontoon (late 16th century). See also at punt