An editing technique which as the name suggests is a quick series of shots linked together to give more of an allusion to something like time passing or the old 'life flashing before my eyes trick'.

Montage (from the French for 'setup; assembly; editing' < monter 'to mount' < Latin mons, montis, 'mountain') has two meanings in film-making, one from the practical, and American, side and one from the theoretical, and European, one. Slavko Vorkapić (link), mentioned above, was best known for creating Vorkapich sequences, or montage in the American sense of the word. Eisenstein, the Russian director, used the term montage in its French sense of an assemblage of shots into a scene. This sense has continued in anglophone film theory.

Ceci n'est pas un seing.