What does adlegation mean?
The definition of adlegation
Ad`le*ga”tion, n.
Etym: [L. adlegatio, allegatio, a sending away; fr. adlegare, allegare, to send away with a commission; ad in addition + legare to send as ambassador. Cf. Allegation.]

A right formerly claimed by the states of the German Empire of joining their own ministers with those of the emperor in public treaties and negotiations to the common interest of the empire. Encyc. Brit.