The LD2 file extension is related to Lingoes dictionary and translation software by Lingoes Project. LD2 files contain compiled language dictionary data from LDF files. They represent a single dictionary that can be imported into Lingoes. Installed dictionaries have LDX files in /dict folder. More dictionaries can be downloaded.
To open LD2 files, install them in Lingoes to add to its library. The Lingoes converter can convert LD2 files to human readable text. LD2 files work on Android and Windows. Apps like GoldenDict Free and Lingoes support LD2 files.
If your system has no apps supporting LD2 files, first download and install one. Lingoes for Windows and GoldenDict Free for Android allow opening LD2 files. After installing, the OS usually automatically associates LD2 files with the new app. If not, manually associate LD2 files with the chosen app.
The LD2 extension may be used by various programs, not just expected ones. Be careful with LD2 files from unknown sources, including potentially harmful software. Check if the LD2 extension is incorrectly specified, as some extensions are very similar.