Order of Magnitude
Etymology
“Magnitude” is from Latin “magnitudo” (greatness), from “magnus” (great); “order” here means a rank or step. The pairing is tied to powers of ten and to logarithmic thinking, and became a staple of scientific and engineering estimation.
noun phrase · /OR-der uhv MAG-nih-tood/
A factor of ten — one order of magnitude means roughly ten times larger or smaller.
What it names
It gives you a coarse but honest gauge of scale, useful when the right question is “ten, hundred, or thousand?” rather than the exact number.
Example
A million is three orders of magnitude larger than a thousand, which is why confusing the two in a budget is not a small slip.
Related idea
It is the everyday cousin of the logarithmic scale: each order of magnitude is one step, so distances that look tiny on a log chart can hide differences of thousands.