[syn: authoritarian, autocratic, dictatorial, despotic, tyrannic, tyrannical]
The Collaborative International Dictionary of English v.0.48:
Tyrannic \Ty*ran"nic\ (?; 277), Tyrannical \Ty*ran"nic*al\, a.
   [L. tyrannicus, Gr. ?: cf. F. tyrannique. See Tyrant.]
   Of or pertaining to a tyrant; suiting a tyrant; unjustly
   severe in government; absolute; imperious; despotic; cruel;
   arbitrary; as, a tyrannical prince; a tyrannical master;
   tyrannical government. "A power tyrannical." --Shak.
   [1913 Webster]
         Our sects a more tyrannic power assume.  --Roscommon.
   [1913 Webster]
         The oppressor ruled tyrannic where he durst. --Pope.
   [1913 Webster] -- Ty*ran"nic*al*ly, adv. --
   Ty*ran"nic*al*ness, .
   [1913 Webster]
WordNet (r) 3.0 (2006):
tyrannical
    adj 1: marked by unjust severity or arbitrary behavior; "the
           oppressive government"; "oppressive laws"; "a tyrannical
           parent"; "tyrannous disregard of human rights" [syn:
           oppressive, tyrannical, tyrannous]
    2: characteristic of an absolute ruler or absolute rule; having
       absolute sovereignty; "an authoritarian regime"; "autocratic
       government"; "despotic rulers"; "a dictatorial rule that
       lasted for the duration of the war"; "a tyrannical
       government" [syn: authoritarian, autocratic,
       dictatorial, despotic, tyrannic, tyrannical]
Moby Thesaurus II by Grady Ward, 1.0:
39 Moby Thesaurus words for "tyrannical":
   absolute, absolutist, absolutistic, arbitrary, aristocratic,
   arrogant, autarchic, authoritarian, authoritative, autocratic,
   bossy, brutal, despotic, dictatorial, domineering, feudal,
   grinding, harsh, heavy-handed, high-handed, imperative, imperial,
   imperious, lordly, magisterial, magistral, masterful, monocratic,
   oppressive, overbearing, overruling, peremptory, repressive,
   roughshod, severe, strict, suppressive, tyrannous, unjust