Girdler \Gir"dler\, n. 1. One who girdles. 2. A maker of girdles. 3. (Zo["o]l.) An American longicorn beetle ({Oncideres cingulatus}) which lays its eggs in the twigs of the hickory, and then girdles each branch by gnawing a groove around it, thus killing it to provide suitable food for the larv[ae].