Lewis & Short

dē-sīdo, sēdi (de-sīdi, Cic. l. l. infra, Lamprid. Alex. Sev. 39, 7), 3, v. n., v. consido.
Of inanimate things, esp. of places, to sink, fall, or settle down.

  1. I. Prop.: tantos terrae motus factos esse, ut multa oppida corruerint, multis locis labes factae sint terraeque desiderint, Cic. Div. 1, 35 fin.; 1, 43, 97; Liv. 32, 9; and poet. of the apparent sinking of mountains to one flying aloft: Gargara desidunt surgenti, Stat. Th. 1, 549: ovum inane natat, plenum desidit, Varr. R. R. 3, 9, 11; Just. 4, 1, 10: ex urina quod desidit album est, sediment, Cels. 2, 7: tumor ex toto desidit, id. 7, 18.
  2. * II. Trop., to deteriorate, degenerate: desidentes mores, Liv. prooem. 9.