The Collaborative International Dictionary of English v.0.48:

Predictable \Pre*dict"a*ble\, a.
   That may be predicted.
   [1913 Webster]

WordNet (r) 3.0 (2006):

predictable
    adj 1: capable of being foretold [ant: unpredictable]

Moby Thesaurus II by Grady Ward, 1.0:

59 Moby Thesaurus words for "predictable":
   anticipatable, anticipated, apt, balanced, calculable, cool,
   dependable, divinable, expected, fair, faithful, faithworthy, fast,
   fiducial, firm, firm as Gibraltar, foreknowable, foreseeable,
   foreseen, foretellable, hopeful, imperturbable, improbable,
   in equilibrium, in the cards, invincible, liable, likely, odds-on,
   precognizable, predictable within limits, presumable, presumptive,
   probable, promising, reliable, secure, solid, sound, stable,
   statistically probable, staunch, steadfast, steady, substantial,
   sure, surefire, trustworthy, trusty, unfailing, unflappable,
   unflinching, unshakable, unwavering, verisimilar, well-balanced,
   well-founded, well-grounded, without nerves