verb tr.: To invest mental or emotional energy in an idea, object, or person.
Back-formation from Greek kathexis (the investment of emotional energy in something). Ultimately from the Indo-European root segh- (to hold) that is also the source of words such as victory (to hold in a battle), hectic, scheme, and scholar.
"Mortimer divorced Jane Goodall's mother, Vanne, in 1950, consigning Jane to the fate of so many children who cathect with the animal kingdom to compensate for missing parents."
Judith Lewis; Observing the Observer: Jane Goodall, The Woman Who Redefined Man; Los Angeles Times; Nov 19, 2006.