Stepping-stone
Pronunciation : Step"ping-stone`
Part of Speech : n.
Definition : 1. A stone to raise the feet above the surface of water or mud in walking.
2. Fig.: A means of progress or advancement. These obstacles his genius had turned into stepping-stones. Macaulay. That men may rise on stepping-stones Of their dead selves to higher things. Tennyson.
Source : Webster's Unabridged Dictionary, 1913