1. a lack or shortage of something that is needed or required
2. a failing or weakness in something

Examples

• The vitamin deficiency caused her to feel tired all the time.
• There is a serious deficiency in the city’s water supply.
• The report highlighted deficiencies in the school’s safety procedures.
• Iron deficiency can lead to anemia.
• The budget showed a deficiency of several thousand dollars.
• His deficiency in math skills held him back in science class.
• The immune deficiency made her more susceptible to infections.