dovetail (n.)

also dove-tail, 1580s, in carpentry, "tenon cut in the form of a reverse wedge," the strongest of all fastenings, from dove (n.) + tail (n.). So called from resemblance of shape in the tenon or mortise of the joints to that of the bird's tail display. As a verb, "to unite by dovetail tenons," 1650s; figuratively "unite closely, as if by dovetails." Related: Dovetailed.