Frecency - Wikipedia
Any heuristic that combines frequency and recency. Can be as simple as nested sort-by, can also be a scoring that combines the two in other ways. See Places and New Frecency for two frecency measures.
prescient.el also implements a frecency heuristic to sort list items in the context of Emacs completing-read menus - or at least it did at one point. The word is mentioned in the selectrum docs but no longer there in the prescient docs.