Alternation

Al·ter·na·tion

Alternation

n.
  1. The reciprocal succession of things in time or place; the act of following and being followed by turns; alternate succession, performance, or occurrence; as, the alternation of day and night, cold and heat, summer and winter, hope and fear.
  2. Permutation. (Math.)
  3. The response of the congregation speaking alternately with the minister.

Phrases & Compounds
Alternation of generation
See under Generation.