Topos (Gk "place"; i.e. "place to find ['invent'] something") referred in classical Greek rhetoric to a standardised method of constructing or treating an argument, i.e. categories that help delineate the relationships among ideas (i.e. stock predicates), and stock concepts. The arguments based on these topoi were divided by Aristotle into "common" and "special" groups:
a. common (categories): laws, witnesses, contracts, oaths, comparisons of similarity, difference, or degree, definitions of things, division of things (whole/parts, for instance), cause and effect, and other items that could be analyzed, researched or documented;
b. special (concepts): justice or injustice, virtue, good, and worthiness.
Curtius expanded this concept in studying topoi as commonplaces: reworkings of traditional material, particularly the descriptions of standardised settings, but extended to almost any literary meme. They might be more-or-less stock characters (ethoi), topics (topoi), settings (kairoi), argument strategies (like types of exposition [logoi] or narratives [mythoi]), etc.
In physics, a topos is something a little different . . .