The definition of a deficiency is something that is lacking, or something that isn't sufficient or good enough.
(noun)When you do not get enough education, this is an example of something that can be seen as a deficiency when you are looking for a job.
See deficiency in Webster's New World College Dictionary
noun
Origin: ME deficience < LL deficientia < L deficiens, prp. of deficere to lack, fail < de-, from + facere, to do
See deficiency in American Heritage Dictionary 4
noun pl. de·fi·cien·cies
Learn more about deficiency