固定 (gùdìng) is a verb meaning 'to fix in place, secure, or fasten' using physical means like screws, brackets, or glue. It contrasts with 安 (to install, fit) which is more about setting up equipment, and 系 (to tie, bind) which implies using rope or string. Use 固定 when the goal is to prevent movement; it covers a broad range of fastening actions.