preposition

(often preceding a date) approximately.

the church was built circa 1860

approximately,about,around,round about,in the region of,roughly,something like,in the area of,in the neighbourhood of,of the order of,or so,or thereabouts,there or thereabouts,more or less,give or take a few,plus or minus a few,nearly,close to,not far off,approaching,getting on for,plus-minus,as near as dammit,in the ballpark of