impeto

An impetus is not a small imp. Impeto is one root of six letters and it has nothing to do with the -et- diminutive: there is no word impo for it to be the little version of. This matters more in Esperanto than in English, because the language really does build dometo from domo and varmeta from varma, so a learner reading imp-et-o is following a habit the language taught them. Here the habit misfires. Read it as a block.

What it actually means. Two related things: the forward drive a person or a project has, and the physical onrush of something moving. Labori kun impeto is to work with drive, in the neighbourhood of energio at 1,142 and vigla at 731. La impeto de la vento is the sheer force of the gust. A subita impeto is a sudden dash, and impete as an adverb means headlong.

One caution for the physicists. English momentum translates as movokvanto in Esperanto's scientific register, and although impeto is sometimes pressed into that job it is not the safe technical term. Keep impeto for the everyday sense, where it competes with nothing and says exactly what you mean.