What word is the same as Ossify?

There isn't one single word that is exactly synonymous with "ossify." However, depending on the context, several words can be used to convey similar meanings:

General meaning (to harden or become rigid):

* Calcify

* Sclerose

* Petrify

* Solidify

* Congeal

* Crystallize

Meaning related to bones:

* Mineralize

* Bone up (informal)

Figurative meaning (to become rigid, inflexible, or unyielding):

* Stagnate

* Rigidify

* Congeal

* Set

* Inflexible

* Unbending

The best choice will depend on the specific context and the intended nuance.