Following Charles Bostick in the May 1974 Word Ways, we define the weight of a letter as its position in the alphabet (A=1, etc.), and the weight of a word as the sum of the weights of its letters. The density of a word is defined as its weight divided by the number of letters in it, so that the density of a word is none other than the average weight of letters it contains.
Word Ways: Vol. 31
, Article 14.
Available at: http://digitalcommons.butler.edu/wordways/vol31/iss3/14