VS Code: Best way to use custom wordlist for autocomplete

I am using VS Code to write markdown files. Is there any way to use a wordlist with technical terms, which is stored in a separate folder outside the opened markdown project, for autocompletion?

At the moment the format of the wordlist with all technical terms is a text file which has on each line a particular term. However, it would be possible to reformat this file if necessary.

You can use the extension Complete from File.

You have to define the languageID and files to use with a configuration in settings.json:

  "complete-from-file.documents": {
    "markdown completions": {
      "documentSelectors": [{ "language": "markdown", "scheme": "file" }],
      "files": [
        "${workspaceFolder}${pathSeparator}markdown-complete.txt",
        "${userHome}${pathSeparator}completions${pathSeparator}markdown-complete.txt"
      ]
    }
  }

Each line of the file is used as a possible completion item. The file can contain comments (// and # lines) and empty lines. A completion line can contain any character (including spaces) but the initial characters must be word characters.

The default is that you need at least 3 characters to get a completion.
This setting can be changed (complete-from-file.minimalCharacterCount).

In Markdown files you have to request a completion with:
Trigger Suggest (key: ctrl+space, commandID: editor.action.triggerSuggest)

If you have that wordlist open in your project, I would think that this setting should help:

Editor: Word Based Suggestions Mode  // set to allDocuments

That should suggest words from all open documents.

But you may need this in your settings.json as well:

  "[markdown]": {
    "editor.quickSuggestions": {
      "other": "on",
      "comments": "on",
      "strings": "on"
    }
  },

(I can't recall why just now but I believe you need special handling for markdown files.) I do get completion suggestions if I do this.

Other wise you would probably have to make your extension with a CompletionProvider which incorporates your wordlist.