lumen1 Syllabification: (lu·men)Pronunciation: /ˈlo͞omən/ (abbreviation: lm)Definition of lumen noun Physics the SI unit of luminous flux, equal to the amount of light emitted per second in a unit solid angle of one steradian from a uniform source of one candela. Origin: late 19th century: from Latin, literally 'light'lumen in other Oxford dictionaries Definition of lumen in the British & World English dictionary
