Dictionary
mile•stone
Pronunciation: (mīl'stōn"), [key]—
n.
1. a stone functioning as a milepost.
2. a significant event or stage in the life, progress, development, or the like of a person, nation, etc.:
Her getting the job of supervisor was a milestone in her career. Random House Unabridged Dictionary, Copyright © 1997, by Random House, Inc., on Infoplease.