a deficiency or failure in neurological or mental functioning
"the people concerned have a deficit in verbal memory"
"they have serious linguistic deficits"
(sports) the score by which a team or individual is losing
"The team faced a significant deficit after conceding three goals in the first half."
an excess of liabilities over assets (usually over a certain period)
"last year there was a serious budgetary deficit"
Deficiency in amount or quality; a falling short; lack.
"The poor lighting created a significant deficit in the overall safety of the stairwell."
In plain English: A deficit is when you have less money than you need to pay your bills.
"The school had to cut programs because their budget deficit was too large."
Usage: Use deficit to describe a specific shortfall where expenses exceed income, such as a budget deficit. Avoid using it interchangeably with general terms like shortage unless referring strictly to financial accounts or measurable quantities that fall below an expected standard.
The word deficit comes from the French déficit, which is derived from the Latin verb deficere. Its original meaning was to fail or fall short.