The Collaborative International Dictionary of English v.0.48:

Sparse \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.
      [1913 Webster]

   2. (Bot.) Placed irregularly and distantly; scattered; --
      applied to branches, leaves, peduncles, and the like.
      [1913 Webster]

The Collaborative International Dictionary of English v.0.48:

Sparse \Sparse\, v. t. [L. sparsus, p. p. of spargere to
   scatter.]
   To scatter; to disperse. [Obs.] --Spenser.
   [1913 Webster]

WordNet (r) 3.0 (2006):

sparse
    adj 1: not dense; "a thin beard"; "trees were sparse" [syn:
           sparse, thin]

Moby Thesaurus II by Grady Ward, 1.0:

64 Moby Thesaurus words for "sparse":
   almost unheard-of, at a premium, broadcast, cheeseparing, chinchy,
   chintzy, diffuse, discrete, dispersed, dispread, disseminated,
   dissipated, distributed, exiguous, in short supply, inappreciable,
   infrequent, insignificant, limited, little, meager, miserly,
   niggardly, not much, occasional, out of print, out of season,
   out of stock, piddling, poor, rare, scant, scanty, scarce,
   scattered, scrimp, scrimping, scrimpy, seldom met with,
   seldom seen, skimp, skimping, skimpy, slim, slow, spare, sparing,
   sporadic, spotty, spread, spread out, sprinkled, stingy,
   straggling, straggly, strewn, strown, thin, tight, uncommon,
   unfrequent, unique, unusual, widespread



The Free On-line Dictionary of Computing (30 December 2018):

sparse

   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.

   (1995-01-16)