The DPD (Digital Pali Dictionary) online now has a feature to search in the definitions specifically that are found in the Chaṭṭha Saṅgāyana Tipiṭaka (CST) commentary.
For those not familiar, a large part of the commentaries is more or less a dictionary of terms found in the text they are commenting on.
There is a teeny tiny tab at the top left corner of the screen:
Then you can search for term definitions as found in the commentary, e.g.:
One thing that wasn’t apparent to me at first is that there are some tips at the bottom of the screen based on what you mouse over:
The detailed documenation is here: