A reference to an aqueduct that was used to supply water to the city of Rome. During the Republic, aqueducts, and the water supplied, were cared for by water companies hired under contract by the censors.

This abbreviation (aq.) is used with several adjectives that have applications for medical or pharmaceutical instructions:

• aq. astr. (aqua astricta), frozen water
• aq. bull. (aqua bulliens), boiling water
• aq. com. (aqua communis), common water
• aq. dest. (aqua destillata), distilled water
• aq. ferv. (aqua fervens), hot water
• aq. frig. (aqua frigida), cold water
• aq. mar. (aqua marina), sea water
• aq. pluv. (aqua pluvialis), rain water
• aq. pur. (aqua pura), pure water
• aq. tep. (aqua tepida), tepid water