Creating an index, via the References tab | Mark Entry, is a manual task, that is, you'd have to create each index entry separately.

What you can do is make use of a concordance as follows: Create a Word document with a two-column table. In the left cell, add the word you want Word to index, in the right cell, add the word you want in the index. Create a new row for each new item you want.

Then use the AutoMark button in the Index dialog box (References tab | Insert Index) to generate the index.

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Stefan Blom
Microsoft Word MVP

Microsoft 365 apps for business
Windows 11 Professional