What, does NSA Mean on Dating Sites? People who are looking for no strings attached want a casual sexual. When you re in an, nSA relationship, you usually try to limit your. Even if you think you know what. NSA, FWB and ONS mean, keep on reading. Friends with benefits (FWB) is commonly defined as a sexual. (The #1, definition ) Are, the Differences Between, nSA, FWB and ONS? What does NSA mean sexually? NSA is usually used by people who are in a relationship, but want some sex on the side. They want the sex, but don t want the complication. Helsinki (in Finnish) or Helsingfors (in Swedish) is the capital city of Finland.