How to say "hoard" in Japanese

• 溜め込むためこむ
  godan verb, transitive verbCovers 'hoard' as ongoing accumulation: the verb also means 'save up' and 'stockpile', so the nuance is things piling up because you keep them rather than use them — money or supplies amassed over time.
  彼かれはずいぶんため込こんだようだ。↗

  He seems to have saved a lot of money.
• しまい込むしまいこむ
  godan verb, transitive verbIts basic senses are 'put away', 'stow away' and 'tuck away'; 'hoard' is an extended use — things put away somewhere and left there. For hoarding as accumulation it is seldom the word you want.
  彼かれは鍵かぎをかけて宝石ほうせきを金庫きんこにしまいこんだ。↗

  He locked up his jewels in the safe.

For 'hoard' as accumulating a stock — saving up or stockpiling until things pile up — use 「溜め込む」; 「しまい込む」 is really about stowing things away, with 'hoard' only a secondary sense, and both are less common choices.

Usage comparisons are AI-assisted and cross-checked by multiple models; for study reference only

• 溜め込むためこむto save up
• しまい込むしまいこむto put away