source: [ゆるゆりの歳納京子たちが並んで歯磨きするGIF画像｜無料GIF画像検索 GIFMAGAZINE 911491]

conditions or practices conducive to maintaining health and preventing disease, especially through cleanliness: 特に清潔さを通して、健康を維持し病気を防ぐことを促す状態や実践

衛生学(hygienics); 健康法

衛生(状態); 清潔(に保つこと)(cleanliness)

e.g. poor standards of food hygiene: 食べ物の衛生状態の乏しい標準

e.g. personal hygiene.: 個人の健康法

late 16th century: via French from modern Latin hygieina, from Greek hugieinē (tekhnē) ‘(art) of health’, from hugiēs ‘healthy’.