strong determination; strong-willed; firmness of purpose
Describes a person or attitude marked by unwavering resolve and firm will. Often used in formal or written contexts.
He is a strong-willed person who sees through whatever he decides.
With firm determination, you can overcome any difficulty.
Yojijukugo composed of 意志 (will, intention) and 堅固 (firm, solid). The combination directly conveys an unyielding will.