alternation

noun9

1. •
   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

   • alternation between night shifts and day shifts
2. •
   The response of the congregation speaking alternately with the minister.
3. •
   A sequence that alternates between positive and negative values.
4. •
   A pattern by which more than one construct is possible, as with "Alice cooked Bob dinner" and "Alice cooked dinner for Bob".
5. •
   The "inclusive or" truth function.
6. •
   A construct in a regular expression that can match any of several specified subexpressions.
7. •
   Ablaut.
8. •
   A type of partial truncation of a polygon, polyhedron or tiling in which alternate vertices are removed.
9. •
   (nonstandard) A permutation.