The Collaborative International Dictionary of English v.0.48:
kissing cousin \kiss"ing cous"in\ A cousin sufficiently well acquainted to be greeted with a kiss; a type of kissing kin. [PJC]WordNet (r) 3.0 (2006):
kissing cousin n 1: a more or less distant relative; familiar enough to be greeted with a kiss [syn: kissing cousin, kissing kin]