IPA: /ɪˈmæk.jə.ləsi/
KK: /ɪˈmæk.jə.lə.si/
The state of being perfectly clean, neat, or free from flaws or mistakes.
The immaculacy of the room impressed all the guests at the party.
Immaculacy is formed from "im-" (meaning not) and "maculatus" (from Latin, meaning spotted or stained) and the suffix "-cy" (meaning state or condition). The word refers to the state of being without spots or stains, hence pure or flawless.
Think of 'not' ('im-') having 'spots' ('maculatus') to remember that immaculacy means being in a state of purity or flawlessness.
No commonly confused words.