breastwork

noun4

1. •
   A fortification consisting of a breast-high bulwark; a parapet.

   • Before long we had flung enough sand-bags into place to make a low breastwork behind which the few men who were on this side of the position could lie down and fire. — 1938
2. •
   A railing on the quarter-deck and forecastle.
3. •
   A parapet.

   • A swarthy boy opened a book and propped it nimbly under the breastwork of his satchel. He recited jerks of verse with odd glances at the text: […] — 1922
4. •
   (slang) Breast augmentation.