Lewis & Short

gĕrŭlus, i, m. [gero].

    1. A. A bearer, carrier: nae ille alium gerulum (argenti) quaerat sibi, Plaut. Bacch. 4, 9, 79; Hor. Ep. 2, 2, 72; Col. poët. 10, 310; Suet. Calig. 40; Sid. Ep. 8, 13; Inscr. Orell. 575; 874; 976; Schol. Juv. 6, 477.
    2. B. One who does something, a doer: gerulus ὁ πράττων, ὁ πρακτήρ, Gloss. Philox.; cf. gerulifigulus.