剛 is built from the 岡 (ridge (in 鋼·綱)) and 刂 (knife (right)) components.
It belongs to a phonetic family with 綱 and 鋼 — they share the 岡 component and the reading コウ.
A common word using 剛 is 金剛 (こんごう), meaning “vajra (indestructible substance); diamond”.
Don't confuse it with 鋼 and 綱.
