to sign, as secretary or other subordinate officer, a writing signed by a principal or superior, in attestation of its authenticity. Thus charters signed by a king are countersigned by a secretary.

COUNTERS, COUTOURS, or COUNTERS, has been used for sergeants at law retained to defend a cause, or to speak for their client in any course of law.

It is of these Chaucer speaks:

A sherif had he been, and a countour, Was nowhere such a worthy vassavour.

They were anciently called serjeant countours.