NOUN (1)

1. a variable quantity that cannot be resolved into components;


ADJECTIVE (2)

1. of or relating to a musical scale;
- Example: "he played some basic scalar patterns on his guitar"

2. of or relating to a directionless magnitude (such as mass or speed etc.) that is completely specified by its magnitude;
- Example: "scalar quantity"

The Collaborative International Dictionary of English v.0.48:

Scalar \Sca"lar\, n. (Math.)
   In the quaternion analysis, a quantity that has magnitude,
   but not direction; -- distinguished from a vector, which has
   both magnitude and direction.
   [1913 Webster]

WordNet (r) 3.0 (2006):

scalar
    adj 1: of or relating to a musical scale; "he played some basic
           scalar patterns on his guitar"
    2: of or relating to a directionless magnitude (such as mass or
       speed etc.) that is completely specified by its magnitude;
       "scalar quantity"
    n 1: a variable quantity that cannot be resolved into components

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

scalar

   1.  A single number, as opposed to a vector or
   matrix of numbers.  Thus, for example, "scalar
   multiplication" refers to the operation of multiplying one
   number (one scalar) by another and is used to contrast this
   with "matrix multiplication" etc.

   2.  In a parallel processor or vector
   processor, the "scalar processor" handles all the sequential
   operations - those which cannot be parallelised or vectorised.

   See also superscalar.

   3.  Any data type that stores a single value
   (e.g. a number or Boolean), as opposed to an aggregate
   data type that has many elements.  A string is regarded as a
   scalar in some languages (e.g. Perl) and a vector of
   characters in others (e.g. C).

   (2002-06-12)