The Free On-line Dictionary of Computing (30 December 2018):

prefix notation prefix syntax(Or "prefix syntax") One of the possible orderings of functions and operands: in prefix notation the function precedes all its operands. For example, what may normally be written as "1+2" becomes "(+ 1 2)". A few languages (e.g., lisp) have strictly prefix syntax, many more employ prefix notation in combination with infix notation. The opposite, postfix notation, is somewhat rarer. (2014-07-08)