stepping stone

English Thesaurus

1. any means of advancement (noun.act)

hypernym	:	agency, means, way,
definition	:	how a result is obtained or an end is achieved (noun.act)

2. a stone in a marsh or shallow water that can be stepped on in crossing (noun.object)

hypernym	:	rock, stone,
definition	:	a lump or mass of hard consolidated mineral matter (noun.object)