1 A circular piece of lignum vitae, hollowed in the centre to take a rope and grooved round the outside to accommodate a strop which enables it to be fixed in position where required. Its main purpose is to change the lead, or direction, of a rope in cases where a block for this purpose is not required.
2 It is also the name given to a piece of thick glass set flush in the deck of a ship to admit light to the deck below.
3 The small expanse of blue sky seen in the centre of a tropical storm.
4 See parrel.