expansion

Look up the expansion of 1018 steel at stick welding temps and figure out how far this thing's gonna bend once we weld it up.

My new office is in the expansion behind the main building.

This expansion requires the original game board.

Mother of mighty Rome's imperial line, / Delight of man, and of the powers divine, / Venus, all-bounteous queen! whose genial power / Diffuses beauty in unbounded store / Through seas, and fertile plains, and all that lies / Beneath the starred expansion of the skies.

Expansion of acronyms is often helpful for nonexpert readers (anacronyms excluded).