inadequacy (n.)

"not equal to what is required, insufficient to effect the end desired," 1670s; see in- (1) "not, opposite of" + adequate. Related: Inadequately.

abstract noun suffix of quality or rank, from Latin -cia, -tia, from Greek -kia, -tia, from abstract ending -ia (see -ia) + stem ending -c- or -t-. The native correspondents are -ship, -hood.