oncost

From on- +‎ cost, or from Middle English uncost (“additional expense”), from Middle Dutch oncost (“expenses, overhead”) (Modern Dutch onkost), equivalent to un- +‎ cost. Cognate with German Unkost (“expenses”).

oncost (plural oncosts)

1. Additional costs; extra expenses.
2. (finance) Overhead (expense)
3. (coal-mining) The cost of upkeep, making and maintaining shafts, roads, pumping, etc.
4. (Britain dialectal, Scotland) The indirect expenditure incurred for the purpose of increasing the productive power of organised labour.

• Coston, nostoc