堅固で美しく、しかも異様な雰囲気を醸し出したのですぐに広まり、室町時代の中頃には普及した。

The solid, beautiful and unusual style caught on rapidly, and was prevalent by the mid Muromachi period. - Wikipedia日英京都関連文書対訳コーパス

末法思想は、『大集経』（正式には『大方等大集経』）の「我が滅後に於て五百年の中は解脱堅固、次の五百年は禅定堅固、次の五百年は読誦多聞堅固、次の五百年は多造塔寺堅固、次の五百年は我が法の中に於て闘諍言訟して白法隠没せん」などを典拠とする。

The source of Mappo shiso is the description of "Daijkkyo Sutra" (officially, "Daihododaijikkyo Sutra" (Mahsamnipata sutra)) saying, 'Gedatsu Kengo (Age of enlightenment) will remain solid for 500 years after my death, Zenjo kengo (the age of meditation) will remain solid for the following 500 years, Dokuju tamon kengo (the age of reading, reciting, and listening) will remain solid for the following 500 years, Tazo toji kengo (the age of building temples and stupas) will remain solid for the following 500 years and in the following 500 years, there will be disputes concerning my teaching and correct teaching will be forgotten.' - Wikipedia日英京都関連文書対訳コーパス

想定不適当事故の見込みを減少させるために競馬場の周り、または、二元的な車線高速道路の中央で建設される堅固な防護壁

a strong protective barrier that is erected around a racetrack or in the middle of a dual-lane highway in order to reduce the likelihood of severe accidents - 日本語WordNet