Word Study
oncost
CIDE DICTIONARY
oncost, n.
In cost accounting, expenditure which is involved in the process of manufacture or the performance of work and which cannot be charged directly to any particular article manufactured or work done (as where different kinds of goods are produced), but must be allocated so that each kind of goods or work shall bear its proper share. [Webster 1913 Suppl.]
For further exploring for "oncost" in Webster Dictionary Online