Something expedient is helpful to you. If you vote your friend in for student body president just because you know she'll hook you up — that's an expedient choice. But expeditious is speedy, like your expeditious exit from the voting booth because you know didn't do the right thing.

Expedient describes a politically advantageous choice. Expedient also describes something that's good for you or something that's useful. It dates back to the 1400s and has its roots in Old French (expedient) and Latin (expedientem). Here are some expedient examples:

On the other hand, expeditious isn't up to anything, it just means speedy or prompt. Expeditious entered English in the late 1400s via expedition, which also has roots in Old French and Latin. If you want to speed things up, use expeditious:

Although expedient and expeditious come from the same Latin root word for "to make ready or to prompt," they parted ways by the 1600s, when expedient became self-serving. Use expedient for "advantageous" and expeditious for "speedy," like how fast you plan for an expedition to Antarctica, or across the street.