The ornamental design for a putterhead, substantially as shown and described.
FIG. 1 is a front elevation of a putter head showing my new design, the
opposite side being a mirror image thereof;
FIG. 2 is a top plan view thereof;
FIG. 3 is a bottom plan view thereof; and
FIG. 4 is a side elevation thereof the opposite side being a mirror image
thereof. The broken line showing of a shaft and grip is for illustrative
purposes only.