charette (n.)

also charrette, c. 1400, "a chariot, a cart," from Old French charrete "wagon, small cart" (12c.), diminutive of charre, from Latin carrum, carrus "wagon" (see car).

Meaning "a concerted effort by concerned individuals to accomplish a given task by marathon work in a defined, short time" is attested by 1977, originally among architects, from French charette (by 1880s in this sense); it is said to be from the jargon of student architects hurrying to finish their models before they would have to be placed in the charrette which collected them for consideration.