N.K. can stand for natural killer cells, neck, no kidding and Nordiska Kompaniet. A natural killer cell is a lymphocyte that serves as an important component of the innate immune system. Nordiska Kompaniet is a Swedish department store that has two locations: one in Stockholm and the other in Gothenburg.
Other possible meanings for N.K. are Nogometni Klub, North Korea and North Kanara. Nogometni Klub is a football club that plays in the Slovenian Prva Liga. N.K. is a possible abbreviation for North Korea, but is not commonly used. DPRK is the more commonly used abbreviation, based on North Korea's official name Democratic People's Republic of Korea. North Kanara is a district in the Indian state of Karnataka.