A "miniature" is 25 moves or less.
Post the best miniatures

A "miniature" is 25 moves or less.
really? oh, didn't know that. is there a link to a page which says that? like a wikipedia article or something?
Well, it conforms to GM Nun's definition:
https://www.amazon.ca/Brilliant-Chess-Miniatures-John-Nunn/dp/1901983161
More broadly, twenty-five moves has long been the traditional limit for including games in collections of miniatures, such as "100 Soviet Chess Miniatures" from the 1960s.
http://www.chessgames.com/perl/chesscollection?cid=1017172
Out of 100 games, 18 are exactly 25 moves long. NONE are longer. That seems like a pretty specific cut-off point.
what