1
general::
In addition to the idiom (see the next entry) ON ONE'S FEET, Also see DEAD ON ONE'S FEET; FALL (LAND) ON ONE'S FEET; GET TO ONE'S FEET; SET ONE BACK ON ONE'S FEET; STAND ON ONE'S FEET; THINK ON ONE'S FEET., 1. Standing, as in I'm tired? I've been on my feet all day. [Mid-1400s] Also see GET TO ONE'S FEET. 2. Also, back on one's feet. Healthy, returned to good health, as in I hope you get back on your feet very soon. [c. 1800]
American Heritage Idioms