| Clumped means the outersole is double thick
from the toe to the arch. This makes for a stiffer, heavier, and longer
lasting shoe. The additional sole leather enables hobnails to be nailed
to the shoe.
Crooked means the shoes are made on separate lasts for the left and right foot, just like modern day shoes. This technique was used in the 18th C. but was not as common as making shoes on straight lasts.
Innersole is the leather extending from toe to heel upon which the foot rests.
Lasts are wooden forms carved in the general shape of a foot. The shoe components (uppers, insole, outsole, heels) are stitched together on the last, and the result is a shoe in the size and width of the last.. Each size and width of shoe needs a separate last. Thus to make shoes from size 7 to 12, with half sizes, in widths D and EE, 24 sets of lasts are needed.
Outersole is the leather extending from toe to heel, under the innersole, and is the leather which wears against the ground.
Welt is a strip of leather sewn to the uppers and innersole. On a welted shoe the outersole is stitched to the welt, which makes it easier to replace the outersole.