The story
From the brand name Bisquick. Blend of biscuit + quick, because the mix was originally sold as a way of making biscuits in "90 seconds from package to oven".
Etymology from Wiktionary, CC BY-SA 4.0.
bisquick
Today it means: Pre-mixed baking mix, generally consisting of flour, a shortening and a leavening agent (for quickly making fresh biscuits, pancakes, dumplings, etc). Full definition →