Expand on the definition of the term 'slug' and what the purpose of a slug is.

Slug is a unit of measurement in the British system and is the counterpart of the SI measurement system, kg. Slug is the measure of mass in UK. in conversion process, 1 slug is equal to 1 lbf s2/ft and a lbf = 1 slug / ft/s2. One slug has a mass of 32.174049 lbm or 14.593903 kg