(no·men·cla·ture) NOUN: The procedure of assigning names to the kinds and groups of organisms listed in a taxonomic classification. In terms of disability, nomenclature refers to ways in which people with disabilities have historically been classified.
(1) Names assigned to kinds and groups of products. (2) Formal designations assigned to products by customer or supplier (such as model number, model type, design differentiation, specific design series, or configuration.)
A gun is normally referred to by the weight of its shell (e.g. 12 pr) or its calibre (e.g. 5 in). When described as '12 pr 6 cwt', the '6 cwt' is the weight of the gun, in the correct sense of that term.