TOP-Seil, certain large sails extended across the topsails by the topsail-yard above, and by the yard attached to the lower mast beneath; being fastened to the former by robands, and to the latter by means of two great blocks fixed on its extremities, through which the topsail-sheets are inserted, passing from thence to two other blocks fixed on the inner part of the yard close
close by the mast; and from these latter the sheets lead downwards to the deck, where they may be slackened or extended at pleasure. See the article SAIL.