Expense
Etymology
From Latin "expensa" (money paid out), from "expendere" (to weigh out) — ex "out" + pendere "to weigh". Romans weighed metal money on scales, so paying was literally weighing it out. The same root gives "pension", "pound", and "expend".
noun · /ik-SPENSS/
Money spent to buy goods, services, or to run a household or business.
What it names
The outflow side of the ledger — each cost that eats into income and must be tracked to know what is truly left over.
Example
Once she logged every small expense, the daily coffees added up to a startling monthly total.
Related idea
Distinguish a capital cost: an expense is consumed in the current period (rent, groceries), while buying a lasting asset like equipment is a capital outlay, spread over the years it serves.