Os and Pubic bone

Os noun - A hard brittle blue-grey or blue-black metallic element that is one of the platinum metals; the heaviest metal known.

Pubic bone and os are semantically related. In some cases you can replace phrase "Pubic bone" with "Os", this terms are similar.

Pubic bone noun - One of the three sections of the hipbone; together these two bones form the front of the pelvis.

Os and pubic bone are semantically related. You can use "Os" instead a noun phrase "Pubic bone".