On one's front and Prone

Prone and on one's front are semantically related In some cases you can use "Prone" instead an adjective phrase "On one's front".

Prone adjective - Having a tendency to be or act in a certain way.

On one's front and prone are semantically related in face down topic. Sometimes you can use "On one's front" instead an adjective "Prone", if it concerns topics such as face downwards.