1. 变成化石：fossilizaiton 化石化 | fossilize 变成化石 | fossilogy 化石学

2. 化石化：fossilization 化石化 | fossilize 化石化 | fossilology 化石学

3. 僵化[陶]：forms of speech 言語形式[陶] | fossilize 僵化[陶] | framing 框架[陶]

4. 使成化石：fossilizationfossilize 固定化 | fossilize 使成化石 | fossilize 变陈腐

verb

1. become mentally inflexible

Synonym: fossilise

2. convert to a fossil

e.g. The little animals fossilized and are now embedded in the limestone

Synonym: fossilise