Abbreviation Meaning / Intended Meaning Category 1/2NS one-half normal saline (0.45%) drug or class name 5-ASA 5-aminosalicylic acid drug or class name a before time A.M. morning time aa of each measurement AAA abdominal aortic aneurysm (called a "triple-A") medical condition AAA apply to affected area route of administration ac before meals time achs before meals and at bedtime time AD right ear route of administration ad lib freely; as much as desired time ad sat. to saturation other ad. to; up to measurement ALT alanine aminotransferase lab alt. alternate time alt. h. every other hour time am, A.M. in the morning; before noon time amp ...