(1) A parenthesis-free notation for forming mathematical expressions in which each operator precedes its operands
WiktionaryText
Noun
A notation for arithmetic (and logical) formulae in which operations (respectively, quantifiers and operands) are written immediately before their operands, used to avoid the need for parentheses; for example, 3 * (4 + 7) is written as * 3 + 4 7 and AANDB is written as ANDAB.
