Definition of reef down:
(v) :
(transitive) To repress.
(v) :
(transitive) To cause not to increase or rise.
(v) :
(transitive) To restrain or control (a sound).
(v) :
(transitive) To retain in the stomach without vomiting.
(v) :
(intransitive) To lie low; to stay concealed by not standing up.
(v) :
(obsolete, printing) To refrain from using capital letters more than absolutely necessary.