granny knot(n = noun.artifact) granny - a reef knot crossed the wrong way and therefore insecure;
is a kind of flat knot, reef knot

barrel knot, black knot, blood knot, bowline knot, clytie knot, cuckold's knot, fisherman's knot, flat knot, french knot, gordian knot, granny, granny smith, knot, loop knot, love knot, lover's knot, lovers' knot, matthew walker knot, overhand knot, pine knot, prolonge knot, reef knot, square knot, stopper knot, surgeon's knot, sword knot, true lover's knot, true lovers' knot, truelove knot, weaver's knot, windsor knot