Meaning

noun a sauce made by adding stock, flour, or other ingredients to the juice and fat that drips from cooking meats

noun the seasoned but not thickened juices that drip from cooking meats; often a little water is added

noun a sudden happening that brings good fortune (as a sudden opportunity to make money)

originFrom Middle English gravey, greavie, gravy; probably from greaves, graves (“the sediment of melted tallow”), or from Old French grave, a claimed misspelling of grané (“stew, spice”), from grain (“spice”). Sense of "pasta sauce" apparently seems to be from Italian dialect, especially Calabrian, differentiating tomato puree (salsa (“sauce”)) from cooked tomato sauce (sugo).

Etymology from Wiktionary, CC BY-SA 3.0