In mathematical texts, we sometimes shorten "Definition" to "Def." and "Definitions" to "Defs." when used with numbers, e.g.:
According to Defs. 1, 2, and 4, ...
We sometimes use similar abbreviations for Figure (Fig., Figs.), Theorem (Thm., Thms.), Problem (Prob., Probs.), Proposition (Prop., Props.), and Corollary (Cor., Cors.). I believe them to be correct. If you disagree, I'd be eager to hear your arguments. (Assume for simplicity that there are no restrictions from the publisher or no publisher at all.)
I'm still fighting with
- Exercise, Exercises
- Example, Examples, and
- Lemma, Lemmas.
How to abbreviate these six words correctly? (Established abbreviations which may or may not be correct from the viewpoint of the English language are treated in a different question.)
P.S. Please don't ask why we wish to to abbreviate. Just take it for granted. Also assume that the publisher (if present) has no restrictions on this.