to let on

Webster's Dictionary (GCIDE)

1.To forbear. [Obs.] --Bacon. [1913 Webster]

2.To be let or leased; as, the farm lets for $500 a year. See note under Let, v. t. [1913 Webster]

To let on, to tell; to tattle; to divulge something. [Low]

To let up, to become less severe; to diminish; to cease; as, when the storm lets up. [Colloq.] [1913 Webster]