From Wiktionary, the free dictionary

From false +‎ work.

falsework (usually uncountable, plural falseworks)

1. (engineering) A temporary framework used in the building of bridges and arched structures in order to hold items in place until the structure is able to support itself.

   • 1955 February, “Notes and News: Construction of River Leen Bridge”, in Railway Magazine, page 140:

     Both steel and timber forms were used, supported on a falsework of steel beams erected on the new abutments at each end and on temporary piles which were driven into the river bed at mid-span.

   • 2024 May 17, “Network News: Viaduct carrying HS2 into Curzon Street takes shape”, in RAIL, number 1009, page 11:

     Each [girder] measuring 38 metres long, they will sit below four steel tripods which will support the falsework and formwork.

2. (engineering) Scaffolding, a temporary frame serving to support and brace a building under construction until it can stand alone.

   • 2003, Erik Larson, The Devil in the White City, page 236:

     ... the woefully incomplete Ferris Wheel ... was a half-moon of steel encased in a skyscraper of wooden falsework.

• falsework on Wikipedia.Wikipedia

• leafworks