IPA: /ˌʌnɪkˈspɛktədnəs/
KK: /ʌnɪkˈspɛktɪnəs/
The condition of something happening that is not anticipated or foreseen.
The unexpectedness of the storm caught everyone off guard.
Unexpectedness → It is formed from "un-" (meaning not), "expect" (from Latin "exspectare", meaning to look out for or await), and "-ness" (meaning the state or quality of). The word "unexpectedness" refers to the quality of not being anticipated or looked out for.
Think of 'not' ('un-') expecting something ('expect') — that's why unexpectedness means the state of not being anticipated.