homo homini lupus [ˈhəʊməʊ ˈhɒmɪnɪ ˈlupəs] int.
1.) The contention that humans are by their nature aggressive and hostile towards each other (Dictionary of Foreign Words, Adrian Room, 2000)
Etymology: Latin, literally man is a wolf to man, from homo, man + homini, dative singular of homo + lupus, wolf. The phrase ultimately derives from Titus Maccius Plautus's Asinaria: Lupus est homo homini, non homo ('A man is a wolf rather than a man to another man').
"This logic also allows us to see what is wrong in the Hobbesian vision of the Monarch as the One who brutally but necessarily imposes peaceful coexistence upon the multitude of individuals who, left to themelves [sic], would descend into a state where homo homini lupus" (Less Than Nothing: Hegel and the Shadow of Dialectical Materialism, Slavoj Zizek, 2012).
Thanks again to the amazing and talented Bibi for the Latin pronunciation!