Verb suffix: it and its inflected forms are found mainly as a rendering of French, Italian, and Latin suffixes like -ire and -iare in borrowings, but it is also sometimes applied with a factitive meaning to German stems.
From Middle High German -ieren, extracted by rebracketing of verbs borrowed from (Old) French, such as parlieren (Old French parlier + -en), or Italian, such as spazieren (Italian spaziare + -en).