To "aspirate" means to:

Aspirating refers to the process of withdrawing fluid or air from a body cavity using suction. This technique is often utilized in medical and technical fields to remove unwanted substances for analysis, to relieve pressure, or to assist in surgical procedures. For example, in a medical context, a physician may aspirate a joint to remove excess fluid that has built up, thereby alleviating pain and improving mobility.

In contrast, the other options focus on different processes. Injecting fluid into a cavity involves adding substance rather than removing it. Administering medication typically refers to the delivery of drugs into a patient, which, although vital in medical practices, does not align with the concept of aspirating. Applying pressure to a wound, while an important first-aid technique, does not involve withdrawing anything and is aimed at controlling bleeding rather than removing fluid or air. Understanding aspirating’s true meaning clarifies its practical applications in both medical and technical scenarios.