The Collaborative International Dictionary of English v.0.48:

Unemotional \Unemotional\
   See emotional.

WordNet (r) 3.0 (2006):

unemotional
    adj 1: unsusceptible to or destitute of or showing no emotion
           [ant: emotional]
    2: cool and formal in manner [syn: restrained, reticent,
       unemotional]

Moby Thesaurus II by Grady Ward, 1.0:

58 Moby Thesaurus words for "unemotional":
   affectless, anesthetized, arctic, autistic, blunt, callous,
   catatonic, chill, chilly, cold, cold as charity, cold-blooded,
   coldhearted, cool, dispassionate, drugged, dull, emotionally dead,
   emotionless, frigid, frosted, frosty, frozen, glacial, hard-boiled,
   hardhearted, heartless, icy, immovable, impassible, impassive,
   indifferent, inexcitable, insusceptible, nonemotional, obdurate,
   objective, obscure, obtuse, out of touch, passionless,
   self-absorbed, soulless, spiritless, unaffectionate,
   uncompassionate, unemphatic, unfeeling, unimpassioned,
   unimpressionable, unloving, unnoticeable, unpassionate,
   unresponding, unresponsive, unsusceptible, unsympathetic,
   untouchable