walker; walking frame; Zimmer frame
A medical assistive device used to support walking, typically for the elderly or people with mobility impairments. 'Zimmer' is a trademarked brand name commonly used in the UK.
My grandmother walks slowly using a walker.
You can borrow a walking frame at the hospital.
Compound of 歩行 (walking) + 補助 (assistance) + 器 (device). A straightforward modern technical term.