apo

adjective1

1. •
   In an inactive, unbound state

   • In this scenario, unbound proteins are predominantly in the ligand-free ("apo") structure. — 2009

noun1

1. •
   Clipping of apolipoprotein.

noun4

1. •
   Air Post Office (both Army and Air Force)
2. •
   Army Post Office
3. •
   Air Force Post Office
4. •
   Initialism of acute pulmonary oedema.