What does "employ" mean?

Employ: To use; to have in service; to cause to be engaged in doing something; -- often followed by in, about, on, or upon, and sometimes by to; as: (a) To make use of, as an instrument, a means, a material, etc., for a specific purpose; to apply; as, to employ the pen in writing, bricks in building, words and phrases in speaking; to employ the mind; to employ one's energies. This is a day in which the thoughts . . . ought to be employed on serious subjects. Addison. (b) To occupy; as, to employ time in study. (c) To have or keep at work; to give employment or occupation to; to intrust with some duty or behest; as, to employ a hundred workmen; to employ an envoy. Jonathan . . . and Jahaziah . . . were employed about this matter. Ezra x.