Lewis & Short

prōcessĭo, ōnis, f. [procedo],

  1. I. a marching onwards, an advance; in sing.: a militibus nostris reditus magis maturus quam processio longior quaereretur, Cic. Imp. Pomp. 9, 24; so in plur., Veg. Mil. 2, 22; of the formal entrance of the consul upon his office, Cod. Just. 12, 3, 4; of the public appearance of the emperor, Capitol. Pertin. 11, 3.
  2. II. A religious procession (late Lat.), Sid. Ep. 5, 17.