The Collaborative International Dictionary of English v.0.48:

Damn \Damn\ (d[a^]m), v. t. [imp. & p. p. Damned (d[a^]md or
   d[a^]m"n[e^]d); p. pr. & vb. n. Damning (d[a^]m"[i^]ng or
   d[a^]m"n[i^]ng).] [OE. damnen dampnen (with excrescent p),
   OF. damner, dampner, F. damner, fr. L. damnare, damnatum, to
   condemn, fr. damnum damage, a fine, penalty. Cf. Condemn,
   Damage.]
   1. To condemn; to declare guilty; to doom; to adjudge to
      punishment; to sentence; to censure.
      [1913 Webster]

            He shall not live; look, with a spot I damn him.
                                                  --Shak.
      [1913 Webster]

   2. (Theol.) To doom to punishment in the future world; to
      consign to perdition; to curse.
      [1913 Webster]

   3. To condemn as bad or displeasing, by open expression, as
      by denuciation, hissing, hooting, etc.
      [1913 Webster]

            You are not so arrant a critic as to damn them [the
            works of modern poets] . . . without hearing.
                                                  --Pope.
      [1913 Webster]

            Damn with faint praise, assent with civil leer,
            And without sneering teach the rest to sneer.
                                                  --Pope.
      [1913 Webster]

   Note: Damn is sometimes used interjectionally, imperatively,
         and intensively.
         [1913 Webster]

The Collaborative International Dictionary of English v.0.48:

Damning \Damn"ing\, a.
   That damns; damnable; as, damning evidence of guilt.
   [1913 Webster]

WordNet (r) 3.0 (2006):

damning
    adj 1: threatening with damnation [syn: damnatory, damning]

Moby Thesaurus II by Grady Ward, 1.0:

45 Moby Thesaurus words for "damning":
   absolute, adducible, admissible, attestative, attestive, authentic,
   based on, certain, circumstantial, conclusive, convincing,
   cumulative, decisive, determinative, documentary, documented,
   evidential, evidentiary, ex parte, eye-witness, factual, final,
   firsthand, founded on, grounded on, hearsay, implicit,
   incontrovertible, indicative, indisputable, irrefutable,
   irresistible, material, nuncupative, overwhelming, presumptive,
   probative, reliable, significant, suggestive, sure, symptomatic,
   telling, valid, weighty