IPA: /ˈædɪkwətnəs/
KK: /ˈædɪkwətnəs/
The quality of being enough or satisfactory to meet a certain standard or need.
The adequateness of the solution was evident in its effectiveness.
Adequateness is formed from "adequate" (from Latin "adaequatus", meaning equal to or sufficient) and the suffix "-ness" (meaning the state or quality of). The word "adequateness" refers to the state of being adequate or sufficient for a purpose.
Think of 'adequate' meaning 'sufficient' and remember that 'adequateness' refers to the quality of being sufficient.