1) In mathematics, scalar (noun) and scalar (adjective) refer to a quantity consisting of a single real number used to measured magnitude (size). Voltage, mass, and temperature measurements can be described as scalar quantities.
2) In Perl programming, a scalar is a variable used to represent a block of information. A scalar can refer to an integer, a float, a string, an object, binary information, or just about anything else. It's a versatile variable that has no length limit and is easily recognizable when looking at Perl code because it is preceded by the symbol "$".