If you have a deficiency, you don't have enough of something that is needed, such as food, water, shelter, or a basic nutrient.
Ex: The doctor told the woman she had an iron deficiency, so she should eat more foods that are high in iron, like red meat, seafood, beans, and green vegetables.
Ex: There is a deficiency of water in many cities in the southwest United States where the climate is hot and dry.
A deficiency can also refer to a problem or flaw in an object or a person.
Ex: That car's deficiency was that it lacked power. It drove smoothly and looked nice, but it took too long to get up to speed on the motorway.
Ex: The presidential candidate's biggest strength was also his biggest deficiency. Although he was a celebrity and everyone knew his name, the people felt he couldn't relate to their average, day to day lives.
A shortage occurs when not enough of something is available. It usually refers to material goods that are bought or sold, but can also refer to other things or even people.
Ex: There was a gasoline shortage when the country's biggest supplier of oil was at war and couldn't transport the oil.
Ex: When I went to the shop this morning, they had a shortage of milk. Everyone must be stocking up for the big storm that is due tonight.
The phrase there is no shortage of something is a sarcastic way of saying there is plenty or more than enough of something.
Ex: There was no shortage of clowns at the circus yesterday. I'm so afraid of them, but every time I turned my head I saw another one!
Ex: When I went to the pet store to look for a new pet, there was no shortage of dogs, but they didn't have any cats.