base plate

Century Dictionary and Cyclopedia

1. n. The foundation-plate of metal on which a heavy piece of machinery, as a steam-engine, stands; the bedplate.
2. n. In base-ball, one of the plates formerly often used to mark the bases; hence, by extension, one of the bases.

GNU Webster's 1913

1. n. the foundation plate of heavy machinery, as of the steam engine; the bed plate.