It means "Filling up"... If we are talking about the TCA cycle, which I am assuming we are. A set of reactions, one of which is the glyoxylate cycle supports the TCA cycle with intermediates that are used in making other molecules, therefore filling in the intermediate that were used in other reactions.
For example, Citrate is used to make Fatty Acids and Cholesterol. When citrate is pulled from the TCA cycle to make these molecules fewer citrate molecules will go through the TCA cycle making less succinate and there for less oxaloacetate. The glyoxylate cycle makes up for this deficit by making succinate, fumarate, and malate which will proceed to complete the TCA cycle.