This is a very interesting one!
きょうりょく (kyouryoku), as it is read, means “cooperation”. But haven’t we saw these kanji before? Yes!
The second kanji (ちから, chikara), means power, strength; the first one is nothing more than the conjugation of three of these “powers” with the kanji 十 (じゅう, jyuu), which means “ten”.
Meaning? Well, we can think of this as the actual meaning of “cooperation”! It is the force gained when ten (many) people join their powers together! Quite easy to memorize right? 🙂