geocachingge‧o‧cach‧ing /ˈdʒiːəʊˌkæʃɪŋ $ ˈdʒiːoʊ-/ noun [uncountable] 
an activity in which people use GPS to find hidden boxes that contain a book that they sign and small objects that they can take in exchange for objects they have brought
an activity in which people use GPS to find hidden boxes that contain a book that they sign and small objects that they can take in exchange for objects they have brought