The Collaborative International Dictionary of English v.0.48:

Stagnate \Stag"nate\ (st[a^]g"n[=a]t), v. i. [imp. & p. p.
   Stagnated (-n[asl]*t[e^]d); p. pr. & vb. n. Stagnating.]
   [L. stagnatus, p. p. of stagnare to stagnate, make stagnant,
   from stagnum a piece of standing water. See Stank a pool,
   and cf. Stanch, v. t.]
   1. To cease to flow; to be motionless; as, blood stagnates in
      the veins of an animal; hence, to become impure or foul by
      want of motion; as, air stagnates in a close room.
      [1913 Webster]

   2. To cease to be brisk or active; to become dull or
      inactive; as, commerce stagnates; business stagnates.
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            Ready-witted tenderness . . . never stagnates in
            vain lamentations while there is any room for hope.
                                                  --Sir W.
                                                  Scott.
      [1913 Webster]