the world > space > shape > curvature > roundness > [noun] > annular quality > ring > binding or confining something (3)
A circular plate or cylindrical ring of timber or iron round the edge of any circular structure (usually to hold it firmly together): (a) a…
A curvilinear wall-plate at the springing of a dome, etc.; = curb, n. 9(a) 8b; also, the plate or frame round the mouth of a well, etc.; the…
Applied to rings, bands, or loops, having similar uses (see quots.); also to other contrivances for binding or confining, as ‘the enclosing case of…