The ornamental design for a nylon cord used as a grass-cutting apparatus of lawn mower, as shown and described.
FIG. 1 is a front elevational view of a nylon cord used as a grass-cutting apparatus of lawn mower showing my new design; the rear elevation view is a mirror image thereof;
FIG. 2 is a right side view thereof; the left side view is a mirror image thereof;
FIG. 3 is a top plan view thereof; the bottom plan view is a mirror image thereof; and,