The term 'BUG's Antenna' is a reference to the antennae of an insect, which are sensory organs used to detect movement and vibrations in the environment. The crossword solution for this term is 'FEELER, ' which refers to the thin, flexible appendages that insects use to sense their surroundings. These feelers are typically located on the head or thorax of the insect and are used to detect changes in temperature, humidity, and air pressure.