\begin{definition}[Definition:Mapping/Also known as]
Words which are often used to mean the same thing as '''mapping''' include:
:'''transformation''' (particularly in the context of self-maps)
:'''operator''' or '''operation'''
:'''function''' (usually in the context of numbers)
:'''map''' (but this term is discouraged, as the term is also used by some writers for '''planar graph''').
Some sources introduce the concept with informal words such as '''rule''' or '''idea''' or '''mathematical notion'''.
Sources which define a '''mapping (function)''' to be only a many-to-one relation refer to a '''mapping (function)''' as a '''total mapping (total function)'''.
Some use the term '''single-valued relation'''.
Sources which go into analysis of multifunctions often refer to a conventional '''mapping''' as:
:a '''single-valued mapping''' or '''single-valued function'''
:a '''many-to-one mapping''', '''many-to-one transformation''', or '''many-to-one correspondence''', and so on.
The wording can vary, for example: '''many-one''' can be seen for '''many-to-one'''.
A '''mapping $f$ from $S$ to $T$''' is also described as a '''mapping on $S$ into $T$'''.
\end{definition}