1. n. [Well Completions]

A chemical additive or inert material used to decrease the density or increase the yield of a cement slurry. The slurry yield is typically expressed in cubic feet of slurry per sack of cement. Increasing the yield reduces the cost per volume of cement slurry, while reducing the slurry density reduces the hydrostatic pressure of the cement column, enabling weak zones to be successfully cemented and isolated.