shortening (n.)

1540s, "action of making short," verbal noun from shorten. Meaning "butter or other fat used in baking" (1796) is from shorten in the sense "make crumbly" (1733), from short (adj.) in the secondary sense of "easily crumbled" (early 15c.), which perhaps arose via the notion of "having short fibers." This is the short in shortbread and shortcake.