scalar(n = noun.cognition) - a variable quantity that cannot be resolved into components;
is a kind of variable, variable quantity
Derived form adjective scalar₂

1.  scalar(a = adj.pert) - of or relating to a musical scale; "he played some basic scalar patterns on his guitar"
Derived form noun scale₆

2.  scalar(a = adj.pert) - of or relating to a directionless magnitude (such as mass or speed etc.) that is completely specified by its magnitude; "scalar quantity"
Derived form noun scalar₁

   In the quaternion analysis, a quantity that has magnitude, but not direction; -- distinguished from a vector, which has both magnitude and direction. [1913 Webster]

scalar, adj. & n. Math. & Physics
--adj. (of a quantity) having only magnitude, not direction.
--n. a scalar quantity (cf. VECTOR).

Etymology:
L scalaris f. scala ladder; see SCALE(3)

scalar field, scalar matrix, scalar product