na-adjective, noun
Describes something physically or structurally sturdy, resilient, and able to withstand pressure or hardship. Often used for materials, systems, or abstract qualities like willpower.
この素材は非常に堅強で、長期間の使用に耐えられる。
This material is extremely robust and can withstand long-term use.
彼の堅強な意志が
His strong will supported the team.