Common abbreviations, searchable both ways, with a warning whenever one abbreviation stands for more than one thing — PM, PT, MS and CC each mean four or five.

1. Pick Word → Abbreviation and type a word (message, manager) to find its abbreviations. The last column lists everything else the same abbreviation means.
2. Pick Abbreviation → Word and type an abbreviation (PM, e.g.) to see every meaning, grouped under the abbreviation. Abbreviations that start with what you typed follow the exact match.
3. Click a blue abbreviation to see all its meanings, or a meaning to see all its abbreviations (number → No., #, num).
4. Narrow with the category buttons, or tick Conflicts only to list just the abbreviations that mean more than one thing.