mesne,
a. [Cf.
Mean intermediate.].
Middle; intervening; as, a mesne lord, that is, a lord who holds land of a superior, but grants a part of it to another person, in which case he is a tenant to the superior, but lord or superior to the second grantee, and hence is called the mesne lord. [1913 Webster]
Mesne process, intermediate process; process intervening between the beginning and end of a suit, sometimes understood to be the whole process preceding the execution. Blackstone. Burrill. -- Mesne profits, profits of premises during the time the owner has been wrongfully kept out of the possession of his estate. Burrill.