1. \Sparse\, a. [Compar. {Sparser}; superl. {Sparsest}.] [L.
   sparsus, p. p. of spargere to strew, scatter. Cf. {Asperse},
   {Disperse}.]
   1. Thinly scattered; set or planted here and there; not being
      dense or close together; as, a sparse population.
      --Carlyle.
   2. (Bot.) Placed irregularly and distantly; scattered; --
      applied to branches, leaves, peduncles, and the like.
   

2. \Sparse\, v. t. [L. sparsus, p. p. of spargere to
   scatter.]
   To scatter; to disperse. [Obs.] --Spenser.
   

A sparse matrix (or vector, or array) is one in which most of the elements are zero. If storage space is more important than access speed, it may be preferable to store a sparse matrix as a list of (index, value) pairs or use some kind of hash scheme or associative memory.