You searched for: “osculation
osculation (s) (noun), osculations (pl)
1. The act of touching each others lips together: Little Susan wondered when she would experience her first osculation with a boy!
2. In mathematics, a contact, as between two curves or surfaces, at three or more common points: In his math class, Mr. Smart explained that an osculation can occur when curves or surfaces touch at which point they have a common tangent.