Source : Webster's Revised Unabridged Dictionary (1913)

Phenomenal \Phe*nom"e*nal\, a. [Cf. F. ph['e]nom['e]nal.]
   Relating to, or of the nature of, a phenomenon; hence,
   extraordinary; wonderful; as, a phenomenal memory. --
   {Phe*nom"e*nal*ly}, adv.

Source : WordNet®

phenomenal
     adj 1: of or relating to a phenomenon; "phenomenal science"
     2: exceedingly or unbelievably great; "the bomb did fantastic
        damage"; "Samson is supposed to have had fantastic
        strength"; "phenomenal feats of memory" [syn: {fantastic}]