What is pieces of timber at a masthead, to which are attached the upper shrouds. At the head of lower masts in large vessels, they support a semicircular platform called the "top." called?

crosstrees — Pieces of timber at a masthead, to which are attached the upper shrouds. At the head of lower masts in large vessels, they support a semicircular platform called the "top.". (Webster's 1913.)

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