Lewis & Short

subter-lābor, lābi, v. dep. n.

  1. I. Lit., to glide or flow under (mostly poet.): fluctus Sicanos, Verg. E. 10, 4: flumina subterlabentia muros, flowing close by, id. G. 2, 157: subterlabens Mosella, Aus. Idyll. 10, 21.
  2. II. Transf., to slip away, escape: celeritate subterlabentem, Liv. 30, 25 (dub.).