countersign

countersign is defined in Webster's Unabridged Dictionary (1913) with 2 senses. The full text of each entry is reproduced verbatim below.

Definitions

  1. 1.The signature of a secretary or other officer to a writing signed by a principal or superior, to attest its authenticity.
  2. 2.(Mil.) A private signal, word, or phrase, which must be given in order to pass a sentry; a watchword.

Source: Webster's Unabridged Dictionary, 1913 edition (public domain, via GCIDE / Project Gutenberg).

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