IPA: /ˌʌndɪˈzaɪərəbəlnəs/
KK: /ʌndɪˈzaɪərəbəl/
The state or quality of being not wanted or not wanted by others.
The undesirableness of the proposal led to its rejection by the committee.
Undesirableness → It is formed from "un-" (meaning not), "desirable" (from Latin "desiderabilis", meaning worthy of desire), and "-ness" (meaning the state of being). The word "undesirableness" refers to the state of not being worthy of desire or being unwanted.
Think of 'not' ('un-') being added to 'worthy of desire' ('desirable') to remember that 'undesirableness' means the state of being unwanted.