外柔内剛[gaijuunaigou] gentle but firm
吸金剛[kokongou] Hevajra
金剛[kongou] vajra (indestructible substance)
金剛薩堕[kongousatta] Vajrasattva
金剛手[kongoushu] Vajrapani

金剛石[kongouseki] diamond
剛の者[gounomono] very strong person
剛臆[gouoku] bravery and cowardice
剛果[gouka] valor and decisiveness (valour)
剛毅[gouki] fortitude