| adjective | (usually followed by `to') not having the necessary means or skill or know-how “unable to get to town without a car” |
| adjective | (usually followed by `to') lacking necessary physical or mental ability “dyslexics are unable to learn to read adequately” |
| adjective | lacking in power or forcefulness “an ineffectual ruler” |
| ineffectiveness | noun | lacking the power to be effective |
| ineffectualness | noun | lacking the power to be effective |
| ineffectuality | noun | lacking the power to be effective |