IPA: /kəmˈpækt.nəs/
KK: /kəmˈpæktnəs/
The quality of being closely packed together or having a small size.
The compactness of the new design makes it easy to store.
Compactness → It is formed from "com-" (meaning together) and "pactus" (meaning to fasten or to make firm) combined with the suffix "-ness" (indicating a state or quality). The word "compactness" refers to the quality of being closely packed together or the state of being firm and dense.
Think of things being 'fastened together' ('pactus') and 'with' ('com-') to remember that 'compactness' means the quality of being closely packed.