/ˈäsəˌfī/
Verb
1. To transform (or cause to transform) from a softer animal substance into bone; particularly the processes of growth in humans and animals. (wiktionary.org)
2. To change (as cartilage) into bone. (merriam-webster.com)
3. To become (or cause to become) inflexible and rigid in habits or opinions. (wiktionary.org)
4. To grow (or cause to grow) formulaic and permanent. (wiktionary.org)
Word origin” Formed from Latin os (genitive ossis) “bone.”