Par'Mach
par'Mach was the Klingon word for love, but "with more aggressive overtones", as Jadzia Dax once explained to Benjamin Sisko.

In 2373, Worf developed par'Mach for Grilka, but was unable to pursue her because at the time he was regarded as a traitor to the Klingon Empire. Instead, he helped Quark conquer Grilka's affections, and eventually realized that Dax was a much more suitable (and attainable) mate. ()

See also
par'Mach'kai
Klingon mating rituals
Klingonese
Emotions