A "sensitive instrument" refers to a device designed to detect and measure small changes in physical quantities, such as temperature, pressure, or light. These instruments are crucial in fields like science, engineering, and medicine, where precise measurements can lead to important discoveries or improvements. For example, a thermometer can accurately measure slight temperature variations, helping doctors diagnose illnesses. These instruments often use advanced technology to enhance their sensitivity. For instance, a microphone can pick up faint sounds, allowing for clear audio recordings. Overall, sensitive instruments play a vital role in enhancing our understanding of the world around us.