(1) In REXX, that part of a compound symbol up to and including the first period. It contains just one period, which is the last character. It cannot start with a digit or a period. A reference to a stem can also be used to manipulate all variables sharing that stem.
(2) The root of an inflected or derived word form that is obtained by stripping off inflectional or derivational affixes, for example: 'polit' is the stem of 'political'. A stem does not have to be a valid word. See also lemma.