x. This common designation for an algebraic unknown is often used by engineers to indicate an indefinite quantity, as in “drink x glasses of water to quench your thirst.” While few nonengineers would miss the meaning of such usage, they would also not overlook the curiosity of it. It is not that the use of the letter as a word is unknown. Indeed, the phrase “x marks the spot” is a cliché. However, the allusion to a spot on a treasure map is a far cry from using an algebraic variable for something mundane.

Engineers bring their jobs home with them, and their language gets dragged along. Why this is so is no doubt due to a variety of factors, not the least significant of which is the fact that engineers usually do their jobs totally surrounded by other engineers, often working on the same or a closely related project. There is little need to draw a distinction between technical and social talk – the latter taking place over the water cooler, the lunch table, or, in the old days, the drafting board – because the audience is the same.

Doctors and lawyers are also prone to lapse into using professional jargon before their patients and clients, but the blank stare or the outright questioning of what is meant usually brings the conversation back into the vernacular.