What does "unfamiliarity" mean?

Lack of familiarity; ignorance or inexperience.

Unfamiliarity

Common synonyms include: agnosticism, alien, alienness, amateurishness, amateurism, blankmindedness.

noun

noun ·6 syllables ·Moderate ·College level

Noun

1
Lack of familiarity; ignorance or inexperience. countable, uncountable
"Due to my unfamiliarity with the library's catalog system, it took several hours to find the book."
2
unusualness as a consequence of not being well known wordnet

"Am I the only one who still feels a sense of unfamiliarity with the word "Surprise party"?"

From un- + familiarity.