### Source : WordNet®

infix notation
n : a notation for forming mathematical expressions using
parentheses and governed by rules of operator precedence;
operators are dispersed among the operands

### Source : Free On-Line Dictionary of Computing

infix notation
One of the possible orderings of {functions} and
{operands}: in infix notation the functions are placed between
their operands, such as "1+2". Although infix notation is
limited to binary functions most languages mix infix notation
with {prefix} or {postfix} notation, as a form of {syntactic
sugar}.
(1997-01-17)