Meaning

noun (theology) the origination of the Holy Spirit at Pentecost

noun the group action of a collection of people or animals or vehicles moving ahead in more or less regular formation

noun the act of moving forward (as toward a goal)

originFrom Middle English processioun, borrowed from Old French pourciession, from Latin prōcessiō (“a marching forward, an advance, in Late Latin a religious procession”), from prōcēdere, past participle prōcessus (“to move forward, advance, proceed”); see proceed.

Etymology from Wiktionary, CC BY-SA 3.0