life, <of an electric lamp>
total time for which an electric lamp has been operated before it becomes useless, or is considered to be so according to specified criteria
Note 1 to entry: The life of an electric lamp is usually expressed in hours.
Note 2 to entry: This entry was numbered 845-07-61 in IEC 60050-845:1987.
Note 3 to entry: This entry was numbered 17-656 in CIE S 017:2011.