ASA
n. countable C1 Advanced US //ˈɑsə// asa
n. a common abbreviation for two different things: a painkiller medicine or a military aircraft. You need the context to know which one is meant.
n. an acronym referring either to acetylsalicylic acid, a common analgesic, or to the United States Army Air Forces. Context determines the specific referent.
She took an ASA for her headache.
The doctor prescribed ASA to reduce the inflammation in his knee.
Historians often study the transition period when the Army Air Forces became a separate branch, marking the end of the ASA era.
Usage
Always written in uppercase letters. Requires context to distinguish between the medical and military senses.