noun
full force; all one's strength
Refers to using every resource or effort available, often in competitive or confrontational contexts.
彼は全勢力を挙げてその問題に取り組んだ。
He tackled the problem with all his might.
全勢力で戦う覚悟だ。
I'm prepared to fight with full force.
Compound of 全 (zen, 'all') + 勢力 (seiryoku, 'force, power, influence'). The word follows standard Sino-Japanese word formation.