Parsing inflected forms may not always work as expected. If the following does not give the correct word, try Latin Words or Perseus.
lessus, acc. um (only in acc. sing.), m., a wailing, cry, funeral lamentation: mulieres genas ne radunto, neve lessum funeris ergo habento, Cic. Leg. 2, 23, 59; but a false reading for pausam, Plaut. Truc. 4, 2, 18.