IPA: //ʌnˈtaɪdɪnəs//
KK: /ʌnˈtaɪdɪnəs/
The state of being messy or not organized.
Her room was filled with untidiness, making it hard to find anything.
Untidiness → It is formed from the prefix "un-" (meaning not) and the root "tidy" (from Old English *tidy*, meaning neat or orderly) combined with the suffix "-ness" (meaning the state or quality of). The word "untidiness" means the state of being not neat or disordered.
Think of 'not' ('un-') being added to 'tidy', which means neat, to remember that 'untidiness' refers to the state of being not neat.