As he grew older, his opinions started to calcify and he refused to accept any changes.

calcify 由词根 calc-（表示"石灰、钙"）和动词后缀 -ify（表示"使...化"）组成，字面意思是"钙化"。在比喻用法中表示思想或态度变得像钙化一样坚硬不化，即"固化、僵化"。