IPA: /ˌʌn.səˈpraɪ.zɪŋ/
KK: /ʌnˈsɜrprɪzɪŋ/
Something that is expected and does not cause surprise.
The ending of the movie was unsurprising because it followed the same pattern as many others.
Unsurprising → It is formed from "un-" (meaning not) and "surprising" (from the verb "surprise", which comes from Old French *surprendre*, meaning to take over or seize). The word "unsurprising" means not causing surprise or not unexpected.
Think of 'not' ('un-') causing a 'seizure' of expectation ('surprise') — that's why unsurprising means something that does not catch you off guard.