IPA: /ˌɛkspɪˈdɪʃəsnəs/
KK: /ɛkˈspɛdɪʃəsnəs/
The quality of being quick and efficient in doing something.
The expeditiousness of the delivery service impressed all the customers.
Expeditiousness → It is formed from "expeditus" (from Latin, meaning unimpeded or free) and the suffix "-ness" (meaning the state or quality of). The word "expeditiousness" refers to the quality of being quick and efficient in action.
Think of being 'unimpeded' ('expeditus') to remember that 'expeditiousness' means the quality of being quick and efficient.