Ambivalence

You might think that ambivalence means wishy-washy or indecisive or whatever. But, no, it means quite the opposite.
 
The word ambivalence has its origins in words meaning strength; in particular, in the Proto-Indo-European (PIE) root wal (to be strong) and later in Latin valere (to be strong) and valentia (strength, vigor).
 
The word ambivalence is a 20th century word. In 1901, the Swiss psychologist Eugen Bleuler coined the word Ambivalenz (based on the model of German Equivalenz; i.e., equivalent) which was created from Latin ambi (both, on both sides) + valentia; i.e., to be strong on both sides. The word ambivalence came to English in 1924 meaning ‘simultaneous conflicting feelings.’
 
The adjective ambivalent was in general use in English by 1929 and meant ‘having simultaneously conflicting feelings or contradictory ideas about an object, person, or action’. Originally the word was a term from psychology but has since taken on a broader literary and general sense.
 
Other words based on the PIE root wal (to be strong) include avail, convalesce, evaluation, invalid, prevalent, valediction, valiance, valid, value, and wield.
 
For a dramatic example of the use of the word ambivalent, check out this ~3.5 minute video clip which was brought to my attention by a colleague. From the 1999 movie, Girl, Interrupted: https://www.youtube.com/watch?v=pvNA2JkMfSI
 
Image: Association for Psychological Science
 
Reference: Online Etymological Dictionary, https://www.etymonline.com/
​