The Collaborative International Dictionary of English v.0.48:
Counterseal \Coun`ter*seal"\ (koun`t[~e]r*s[=e]l"), v. t. [imp. & p. p. Countersealed (koun`t[~e]r*s[=e]ld"); p. pr. & vb. n. Countersealing.] To seal or ratify with another or others. --Shak. [1913 Webster]