Undoubtedly pronounced as a
contraction of "lighter wood". Also known as "fat lighter", it is the
knotty remnant of a particularly
resinous variety of
conifer, the longleaf pine. Also known as "fat pine", or "heart pine", the longleaf pine is prized for its strength and
resistance to
insects and
rot. It is found in
abundance throughout the southern United States.
The lighter'd knot is best known as an excellent source of fuel, mainly utilized as kindlin' wood for fires. Most Southerners prefer to cook and heat with hardwood such as oak, which is notoriously difficult to ignite. The lighter'd knot solves this problem, as it contains a tremendous amount of flammable resin. One relatively small piece of lighter'd can be lit easily with a match and used to start a very large pile of even green oak. It may also be used as an excellent torch.
The knots have traditionally been gathered in old-growth forests, usually found lying under the canopy of younger trees. The best source of lighter'd knots is from a tree that has been struck by lightning or otherwise killed in the winter when its sap is down. Not only do these yield the relatively modest lighter'd knots, but massive lighter'd stumps as well.
These stumps have become an important source of a certain nitrate compound that is used in the production of dynamite and other high explosives. This is not surprising to anyone who has ever witnessed the jet engine-roar of a few good knots in the fireplace.
The lighter'd knot burns with a very hot but sooty flame, due to its high hydrocarbon content. This phenomenon has given rise to the maritime phrase "looks like she's runnin' on lighter'd knots", in reference to the black exhaust of a poorly-tuned diesel engine.