ossifies

third-person singular simple present indicative of ossify

(ambitransitive) To transform (or cause to transform) from a softer animal substance into bone; particularly the processes of growth in humans and animals.
(ambitransitive, animate) To become (or cause to become) inflexible and rigid in habits or opinions.
(ambitransitive, inanimate) To grow (or cause to grow) formulaic and permanent.
(rare) To calcify.