费用 (fèi yòng) is a compound noun meaning 'expenses' or 'cost' — the money required to pay for something. The first character, 费 (fèi), means 'to expend' or 'expense', and the second, 用 (yòng), means 'use' or 'usage'; together they convey the idea of 'money used' or 'expenditure'. It is a formal, neutral term commonly used in financial, administrative, and everyday contexts — such as discussing medical bills, travel budgets, tuition, or service charges.

Unlike colloquial terms like 花费 (huā fèi) — which emphasizes the act of spending — 费用 refers specifically to the amount or category of money involved. It often appears after classifiers (e.g., 一笔费用, 'a sum of expenses') or with verbs like 支付 (zhī fù, 'to pay') or 包含 (bāo hán, 'to include'). It’s frequently pluralized implicitly (no plural marker needed) and rarely used in isolation without context.