The Collaborative International Dictionary of English v.0.48:
Overload \O`ver*load"\, v. t. [imp. & p. p. Overloaded; p. pr.
& vb. n. Overloading.] [Cf. Overlade.]
To load or fill to excess; to load too heavily.
The Free On-line Dictionary of Computing (30 December 2018):
(Or "Operator overloading"). Use of a single
symbol to represent operators with different argument types,
e.g. "-", used either, as a monadic operator to negate an
expression, or as a dyadic operator to return the difference
between two expressions. Another example is "+" used to add
either integers or floating-point numbers. Overloading is
also known as ad-hoc polymorphism.
User-defined operator overloading is provided by several
modern programming languages, e.g. C++'s class system and
the functional programming language Haskell's type
Ad-hoc polymorphism (better described as overloading) is the
ability to use the same syntax for objects of different types,
e.g. "+" for addition of reals and integers or "-" for unary
negation or diadic subtraction. Parametric polymorphism
allows the same object code for a function to handle arguments
of many types but overloading only reuses syntax and requires
different code to handle different types.