noun The reciprocal succession of (normally two) things in time or place; the act of following and being followed by turns; alternate succession, performance, or occurrence
the alternation of day and night
noun The response of the congregation speaking alternately with the minister.
noun Ablaut.
noun A pattern by which more than one construct is possible, as with "Alice cooked Bob dinner" and "Alice cooked dinner for Bob".
dative alternation; locative alternation
noun The "inclusive or" truth function.
noun A sequence that alternates between positive and negative values.
noun A permutation.
noun A construct in a regular expression that can match any of several specified subexpressions.