late 14c., "to speak or act for the glory or honor (of someone or something)," from Old French magnefiier "glorify, magnify," from Latin magnificare "esteem greatly, extol, make much of," from magnificus "great, elevated, noble" (see magnificence). Meaning "use a telescope or microscope" is first attested 1660s, said to be a unique development in English. Related: Magnified; magnifying.