D defs.my
Entry 3 senses · 2 variants Webster, 1913

Countersign

/(-s?n`; 277)/ · Coun·ter·sign · IPA
01 v. t. To sign on the opposite side of (an instrument or writing); hence, to sign in addition to the signature of a principal or superior, in orde…
imp. & p. p. Countersigned; p. pr. & vb. n. Countersigning
  1. 1.
    To sign on the opposite side of (an instrument or writing); hence, to sign in addition to the signature of a principal or superior, in order to attest the authenticity of a writing.
02 a. The signature of a secretary or other officer to a writing signed by a principal or superior, to attest its authenticity.
  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.
    A private signal, word, or phrase, which must be given in order to pass a sentry; a watchword.(Mil.)