Disperser

A disperser is a one-sided extractor. Where an extractor requires that every event gets the same probability under the uniform distribution and the extracted distribution, only the latter is required for a disperser. So for a disperser, an event $$A \subseteq \{0,1\}^{m}$$ we have: $$Pr_{U_{m}}[A] > 1 - \epsilon$$

Definition (Disperser): A $$(k, \epsilon)$$-disperser is a function

$$Dis: \{0,1\}^{n}\times \{0,1\}^{d}\rightarrow \{0,1\}^{m}$$

such that for every distribution $$X$$ on $$\{0,1\}^{n}$$ with $$H_{\infty}(X) \geq k$$ the support of the distribution $$Dis(X,U_{d})$$ is of size at least $$(1-\epsilon)2^{m}$$.

Graph theory
An (N, M, D, K, e)-disperser is a bipartite graph with N vertices on the left side, each with degree D, and M vertices on the right side, such that every subset of K vertices on the left side is connected to more than (1 &minus; e)M vertices on the right.

An extractor is a related type of graph that guarantees an even stronger property; every (N, M, D, K, e)-extractor is also an (N, M, D, K, e)-disperser.

Other meanings
A disperser is a high-speed mixing device used to disperse or dissolve pigments and other solids into a liquid.