Noun substitution has 2 senses
  1. substitution, permutation, transposition, replacement, switch - an event in which one thing is substituted for another; "the replacement of lost blood by a transfusion of donor blood"
    --1 is a kind of variation, fluctuation
    Derived forms: verb substitute2, verb substitute1
  2. substitution, exchange, commutation - the act of putting one thing or person in the place of another: "he sent Smith in for Jones but the substitution came too late to help"
    --2 is a kind of change
    --2 has particulars:
     replacement, replacing; subrogation; weaning, ablactation
    Derived form: verb substitute1