～器
～き · ～ki · JLPT N2 · noun
device
🔌 器: four 口 vessels guarded by a 犬 dog, so containers, then tools
器 first meant vessels and containers. As a suffix it names the device for a job: 炊飯器 rice cooker, 楽器 musical instrument, 消火器 fire extinguisher, 食器 tableware. Sound hook: ki sounds like key, the key tool for the task.