适用
shìyòng · HSK 3
apply
✅ 适 (suitable) + 用 (use) = suitable for use → applicable
适 means fitting/suitable and 用 means to use, so 适用 literally reads as suitable-to-use. Common in formal contexts: laws, rules, or tools that 适用 to a situation are the ones that apply.
用 — pictograph of a bucket or wooden pail
用 originally depicted a bucket or container, possibly a sacrificial vessel made of wood. Over time it was borrowed to mean 'to use' or 'employ,' losing its concrete object sense. The modern meaning 'use' has been standard since early classical Chinese.