用いる
もちいる · mochiiru · JLPT N3 · verb-ichidan
to use
🔧 mochi-iru: from 持ち (mochi, hold) + 率る (iru, take along), hold it and use it
The usual etymology traces 用いる to 持ち率る: 持ち means holding something and 率る means taking it along with you. If you hold something and bring it with you, you mean to use it. The kanji 用 means use, the same as in Chinese 用 yòng.
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.