deadeye

noun, plural dead·eyes.

1. Nautical. either of a pair of disks of hardwood having holes through which a lanyard is rove: used to tighten shrouds and stays.
2. an expert marksman.

noun

1. nautical either of a pair of disclike wooden blocks, supported by straps in grooves around them, between which a line is rove so as to draw them together to tighten a shroudCompare bull’s-eye (def. 9)
2. mainly US informal an expert marksman