# UNDEFINE Command [GstarCAD 2018](Help%20System/GSTARCAD/2018/Index.md) → [Commands](Help%20System/GSTARCAD/2018/Commands/(Commands).md) → [U](Help%20System/GSTARCAD/2018/Commands/U/(U).md) The UNDEFINE command is used to allow the command defined by application program to replace the internal command. **Command Access:** > **Command:** UNDEFINE Command Prompts: > Enter command name: Function Description: Users could forbid a command by inputting the command name under the UNDEFINE command prompt. The forbidden command could be redefined to execute other functions. ## Other versions with matching text [GstarCAD 2016](../../../2016/Commands/U/UNDEFINE%20Command--a449a7f71c52.md) · [GstarCAD 2017](../../../2017/Commands/U/UNDEFINE%20Command--a449a7f71c52.md) · [GstarCAD 2019](../../../2019/Commands/U/UNDEFINE%20Command--a449a7f71c52.md) · [GstarCAD 2020](Help%20System/GSTARCAD/2020/Commands/U/UNDEFINE%20Command--a449a7f71c52.md) · [GstarCAD 2021](../../../2021/Commands/U/UNDEFINE%20Command--a449a7f71c52.md)