• 足あし — foot / leg
• 足音あしおと — footsteps
• 足元あしもと — at one’s feet
• 足たりる — to be enough
• 不足ふそく — shortage
• 遠足えんそく — excursion / school trip

“足” is easy to remember by thinking of feet in motion or the idea of being “enough” to complete a journey. It’s useful both for physical expressions and abstract ones like quantity or satisfaction.

足あしが 速はやいです。
He is fast on his feet.

睡眠すいみんが 不ふ足そくしています。
I haven’t had enough sleep.