Definition, synonyms and related words
Air Post Office (both Army and Air Force)
"The vintage letter was sent via apo during World War II to reach soldiers overseas quickly."
"The ship was forced to make an emergency stop at an isolated apo in the middle of the Pacific Ocean where no supplies were available for weeks."
In an inactive, unbound state
"The enzyme exists in its apo form when it lacks a bound cofactor and cannot catalyze reactions."
In plain English: Apo means something that is away from or separate from its original position.
"The situation left him feeling completely alone and without any support from his family."