Definition of countersignature in US English:

countersignature

noun

  • A signature added to a document already signed by another person.

    ‘no decision can be made without the countersignature of a senior colleague’
    ‘he altered invoice details and faked a countersignature’

Pronunciation

countersignature

/ˌkoun(t)ərˈsiɡnəCHər//ˌkaʊn(t)ərˈsɪɡnətʃər/