The Collaborative International Dictionary of English v.0.48:

Quell \Quell\, v. i. [imp. & p. p. Quelled; p. pr. & vb. n.
   Quelling.] [See Quail to cower.]
   [1913 Webster]
   1. To die. [Obs.]
      [1913 Webster]

            Yet he did quake and quaver, like to quell.
                                                  --Spenser.
      [1913 Webster]

   2. To be subdued or abated; to yield; to abate. [R.]
      [1913 Webster]

            Winter's wrath begins to quell.       --Spenser.
      [1913 Webster]

WordNet (r) 3.0 (2006):

quelled
    adj 1: subdued or overcome; "the quelled rebellion"; "an
           uprising quenched almost before it started"; "a squelched
           rumor" [syn: quelled, quenched, squelched]

Moby Thesaurus II by Grady Ward, 1.0:

39 Moby Thesaurus words for "quelled":
   broken, brought low, chastened, conquered, constrained, controlled,
   crushed, domesticated, felled, flattened, housebroke, housebroken,
   humbled, humiliated, hushed, in control, in hand, limited,
   made to grovel, mastered, put down, quashed, reduced, repressed,
   restrained, smashed, smothered, softened, squashed, squelched,
   stable, stifled, subdued, subjugated, suffocated, suppressed,
   tamed, tempered, vanquished