Origin

The character 剛 combines two parts to express the idea of strength. On the right is the knife radical (刂), which marks characters related to cutting, hardness, or sharp force — qualities associated with sturdiness. On the left, 岡 serves as a sound hint, telling you roughly how to pronounce the character (as ゴウ), rather than contributing to the meaning. Together, the knife radical grounds the sense of physical strength while the sound component helps anchor the pronunciation.