Fairlead

A fairlead is a block, padeye, ring or any other device which controls the path of a line on a boat.

When a line is not running correctly where it is supposed to go, or is snagged or stuck, it is said to be "fouled". When a line is running correctly and is not fouled, it is said to be "fair".

A fairlead is simply a device that "leads" a line "fair".

A padeye is a type of fairlead. It is any sort of ring or loop that is fastened to the deck or a spar through which a line is run. Lines should only be run through padeyes at shallow angles. For sharp angles (especially when heavy loads are required), a block should be used.