Mid 17th century. In sense 1, occurring as a graphic abbreviation for post-classical Latin aquaaqua in various post-classical Latin and borrowed phrases, as aqua regia, etc.
Definition of aq. in US English:
aq.
nounak
rare
Chemistry and Medicine= "aqua".
Origin
Mid 17th century. In sense 1, occurring as a graphic abbreviation for post-classical Latin aqua aqua in various post-classical Latin and borrowed phrases, as aqua regia, etc.