Search Result for "grandfather clause":
Wordnet 3.0

NOUN (1)

1. an exemption based on circumstances existing prior to the adoption of some policy; used to enfranchise illiterate whites in south after the American Civil War; 



WordNet (r) 3.0 (2006):

grandfather clause
    n 1: an exemption based on circumstances existing prior to the
         adoption of some policy; used to enfranchise illiterate
         whites in south after the American Civil War