(1):

(n.) Any thimble-shaped appendage or fixure.

(2):

(n.) A tubular piece, generally a strut, through which a bolt or pin passes.

(3):

(n.) A fixed or movable ring, tube, or lining placed in a hole.

(4):

(n.) A tubular cone for expanding a flue; - called ferrule in England.

(5):

(n.) A ring of thin metal formed with a grooved circumference so as to fit within an eye-spice, or the like, and protect it from chafing.

(6):

(n.) A kind of cap or cover, or sometimes a broad ring, for the end of the finger, used in sewing to protect the finger when pushing the needle through the material. It is usually made of metal, and has upon the outer surface numerous small pits to catch the head of the needle.