A person who cannot or does not work efficiently.
"The project manager fired Tom because he was too inefficient to meet any deadlines despite working twelve-hour days."
not producing desired results; wasteful
"an inefficient campaign against drugs"
"outdated and inefficient design and methods"
lacking the ability or skill to perform effectively; inadequate
"an ineffective administration"
"inefficient workers"
Not efficient; not producing the effect intended or desired; inefficacious
"The new energy-saving bulb was inefficient because it flickered constantly and failed to brighten the room as advertised."