The Klingon term for love, carrying more aggressive overtones than the human idea, which gives its name to the episode in which Worf helps Quark court Grilka.
Par'Mach is the Klingon word for love. Jadzia Dax explains that it implies something much more forceful than the human notion. Klingon courtship involves challenge, poetry, thrown objects and a fair chance of injury.
The term comes from Looking for par'Mach in All the Wrong Places in 2373. Grilka returns to Deep Space 9 and Worf is smitten, but as a dishonoured Klingon he cannot court her. He ends up coaching Quark, whom she actually favours, in Klingon romance and in the use of a bat'leth, finally controlling the Ferengi's movements remotely in a duel with her retainer Thopok.
Dax points out to Worf that he has been ignoring someone much closer to hand. By the end of the episode the two of them are in the infirmary with Quark and Grilka, all four being treated for injuries.