de ‧ fi ‧ cien ‧ cy /dɪˈfɪʃ ə nsi/ BrE AmE noun ( plural deficiencies ) [uncountable and countable] formal
1 . a lack of something that is necessary SYN shortage
deficiency of
a deficiency of safe play areas for children
iron/vitamin etc deficiency
Some elderly people suffer from iron deficiency in their diet.
2 . a weakness or fault in something
deficiency in
There are deep deficiencies in this law.