资料来源 : Webster's Revised Unabridged Dictionary (1913)

Preexist \Pre`["e]x*ist"\, v. i. [imp. & p. p. {Pre["e]xisted};
   p. pr. & vb. n. {Pre["e]xisting}.]
   To exist previously; to exist before something else.

资料来源 : WordNet®

preexisting
     adj : existing previously or before something; "variations on
           pre-existent musical themes" [syn: {preexistent}, {pre-existent},
            {pre-existing}]