mechanics

Here the -s is a genuine plural. It takes a plural verb (the mechanics are on strike) and can be counted. It carries every meaning of mechanic: the garage technician, the historical sense of any manual worker, the slang hitman and the cheat who manipulates cards or dice. In game design it names individual rules, where it comes close to the workings of something.

The word usually takes of here: the mechanics of a board game, the mechanics of word processing. It means the practical, how-it-works side of a thing. Games blur the line, because the plural of mechanic also names individual gameplay rules. A game can have one mechanic among several, but the workings sense is uncountable and has no singular.

Physics borrowed this name from the workshop: Latin mēchanicus, from Greek mēkhanḗ, "machine, tool". The science is traditionally divided into statics, kinematics and dynamics, and it underpins both classical and quantum descriptions of matter. Despite the final -s, it is uncountable and takes a singular verb, as physics does: mechanics explains, not mechanics explain.

Teachers and editors use this word for the surface of a text: spelling, punctuation, capitalization and the like. It is usually set against higher-order concerns such as content, organization and style. That contrast lets a reader praise an essay's ideas while still faulting its mechanics, and it keeps a proofreading pass separate from a structural edit.