We claim the ornamental design for a utility knife, as shown and described.
FIG. 1 is a top, front and left side perspective view of a utility knife embodying the new design, wherein the blade mechanism is in the extended position;
FIG. 2 is a top, rear and right side perspective view thereof;
FIG. 3 is a left side elevation view thereof;
FIG. 4 is a right side elevation view thereof;
FIG. 5 is a top plan view thereof;
FIG. 6 is a bottom plan view thereof;
FIG. 7 is a rear elevation view thereof;
FIG. 8 is a front elevation view thereof; and,
FIG. 9 is a top, front and left side elevation view, wherein the blade mechanism is in the retracted position.
The shading lines shown in the drawings represent the approximate three-dimensional contour of the design, and are not intended to indicate surface decoration.
The broken line showings of the blade form no part of the claimed design.