inefficient
1. [ adjective ] not producing desired results; wasteful
Examples:

"an inefficient campaign against drugs" "outdated and inefficient design and methods"

Related terms: efficient uneconomical ineffective incompetent
2. [ adjective ] lacking the ability or skill to perform effectively; inadequate
Synonyms: ineffective
Examples:

"an ineffective administration" "inefficient workers"

Related terms: incompetent
Similar spelling:   inefficiently
  inefficiency
  inefficacious
  inefficacy
  in_effect