WordNet sense 1 (the cardinal number that is the product of ten and five):

fifty

WordNet sense 2 (a cgs unit of illumination equal to the brightness of a perfectly diffusing surface that emits or reflects one lumen per square centimeter):

lambert

WordNet sense 3 (a metric unit of capacity equal to the volume of 1 kilogram of pure water at 4 degrees centigrade and 760 mm of mercury (or approximately 1.76 pints)):

liter, litre, cubic decimeter, cubic decimetre

WordNet sense 4 (the 12th letter of the Roman alphabet):

letter l

WordNet sense 5 (being or denoting a numerical quantity but not order):

cardinal