ambivalence:
"simultaneous conflicting feelings," 1924, from Ger. Ambivalenz, coined 1910 by Ger. psychologist Eugen Bleuler (on model of equivalence, etc.) from L. ambi- "both" + valentia "strength," from prp. of valere "be strong" (see valiant). A psychological term that by 1929 had taken on a broader literary and general sense. Ambivalent first recorded 1916.