1.
military strength; fighting power
The combat capability or armed forces of a nation or military unit.
2.
key player; valuable asset; contributor
A person who is a major contributor to a team, company, or project. Figurative extension of the military sense, commonly used in sports and business.
In the context of Japan's constitution, Article 9 famously states that Japan renounces 戦力の保持 (the maintenance of war potential). In everyday use, the figurative sense (sense 2) is very common, especially in sports and business. Key compounds: 即戦力 (someone who can contribute immediately), 戦力外 (not a contributor; dropped from the team roster).
Related Words
Compare:
兵力 (military strength)
Related:
軍事力 (military strength)
Compare:
防衛力 (defensive capability)
Compare:
総合力 (overall ability)