festival vendor; stallholder at a temple fair
Refers to a merchant who sets up a stall on a 縁日 (temple or shrine festival day). The term is straightforward and neutral.
Festival vendors lined up in rows within the temple grounds.
縁日 is the festival day itself, while 縁日商人 is the person who sells goods there.
露天商 is a more general term for a street vendor or stallholder, not limited to temple festivals.
Compound of 縁日 (temple festival day) and 商人 (merchant). The exact historical derivation is straightforward.