Question

What is American english for constable

Answer 1

Here is your answer

American English for constable means police officer in lower rank

Answer 2

The American English for the word constable is police officer.

Constable is mostly a UK word which means the lowest ranked police.

In USA the lowest police officer is of the same rank of a constable.

However, the word constable is probably a derivation of German word.  

The duty of the constable is mostly helping in implementing the basic duty of police.