An Engineer's Vocabulary: Delta

The engineers at work, our customers, and our suppliers employ English in some pretty interesting ways sometimes. If you want to impress an engineer, or at least to make headway in convincing him that you aren't an idiot, throwing these terms into your every day speech can be helpful. I thought I'd try to help you out by occasionally posting some of the phrases I hear most often. Today's word is Delta.

Pretty much everyone who was forced to take physics at one time has seen the capital Greek letter Delta used to show a net difference between two measurements (for example, the difference in speed measured at one time and speed measured later). In this case, we'd normally say "What is Delta x?" There is nothing unusual about using Delta in this way--it's just shorthand for "What is x2 - x1?"

Engineers use Delta as a noun, by itself, whenever they're interested in how a value may change. It's as if we have not actually learned the words "difference" or "change." I can understand the latter, since as a whole, engineers tend to be politically conservative, but they've definitely taken enough math to have learned "difference." Here's an example of how to use this term correctly in every-day conversation:

Bob: "Larry, we thought the zebras would be home at 9:00, but it sounds like they'll be late."
Larry: "Really? What's the delta?"

So now you have a little insight into the secret language of engineers. Use it well!