sklɛˈrɑːtɪk
Here's a breakdown:
* skl as in "school"
* ɛ as in "bed"
* r as in "road"
* ɑː as in "father"
* tɪk as in "tick"
You can hear it pronounced here: [https://dictionary.cambridge.org/dictionary/english/sclerotic](https://dictionary.cambridge.org/dictionary/english/sclerotic)