Capacity describes your ability to do something or the amount something can hold. If your bird cage is at full capacity, you can't stuff one more feathered friend in there without causing birdie claustrophobia.

From the Latin word capacitatem meaning “breadth, capacity,” capacity is a noun that in the simplest sense means "ability" or "capability": the capability of a room to hold a certain number of people, the ability of a law to change crime rates, your ability to pick up foreign languages. You might hear about factories working at "full capacity" — that means at full speed, producing as much as they possibly can.

Definitions of capacity
  1. noun
    capability to perform or produce
    “among his gifts is his capacity for true altruism”
    “limited runway capacity
    “a great capacity for growth”
    see moresee less
    lack of physical or natural qualifications
    type of:
    capability, capableness
    the quality of being capable -- physically or intellectually or legally
  2. noun
    a specified function
    “he was employed in the capacity of director”
    “he should be retained in his present capacity at a higher salary”
    see moresee less
    type of:
    function, office, part, role
    the actions and activities assigned to or required or expected of a person or group
  3. noun
    the amount that can be contained
    “the gas tank has a capacity of 12 gallons”
    synonyms: content
    see moresee less
    vital capacity
    the maximum amount of air that can be exhaled after a maximum inhalation (usually tested with a spirometer); used to determine the condition of lung tissue
    type of:
    the amount of 3-dimensional space occupied by an object
  4. noun
    (computer science) the amount of information (in bytes) that can be stored on a disk drive
    “the capacity of a hard disk drive is usually expressed in megabytes”
    see moresee less
    formatted capacity
    (computer science) the usable capacity of a disk drive; the amount of space that is left after the sector headings and boundary definitions and timing information have been added by formatting the disk
    unformatted capacity
    (computer science) the total number of bytes on a disk including the space that will be required to format it
    type of:
    indefinite quantity
    an estimated quantity
  5. noun
    the maximum production possible
    “the plant is working at 80 per cent capacity
    see moresee less
    type of:
    (economics) manufacturing or mining or growing something (usually in large quantities) for sale
  6. noun
    tolerance for alcohol
    see moresee less
    type of:
    the power or capacity of an organism to tolerate unfavorable environmental conditions
  7. noun
    the power to learn or retain knowledge; in law, the ability to understand the facts and significance of your behavior
    synonyms: mental ability
    see moresee less
    lack of intellectual power
    prescience, prevision
    the power to foresee the future
    type of:
    ability, power
    possession of the qualities (especially mental qualities) required to do something or get something done
  8. noun
    an electrical phenomenon whereby an electric charge is stored
    synonyms: capacitance, electrical capacity
    see moresee less
    type of:
    electrical phenomenon
    a physical phenomenon involving electricity
  9. noun
    the susceptibility of something to a particular treatment
    synonyms: capability
    see moresee less
    the capacity of an organism to defend itself against harmful environmental agents
    (chemistry) the capacity of a substance to take part in a chemical reaction
    type of:
    susceptibility, susceptibleness
    the state of being susceptible; easily affected
Word Family

Test prep from the experts

Boost your test score with programs developed by’s experts.

  • Proven methods: Learn faster, remember longer with our scientific approach.
  • Personalized plan: We customize your experience to maximize your learning.
  • Strategic studying: Focus on the words that are most crucial for success.


  • Number of words: 500+
  • Duration: 8 weeks or less
  • Time: 1 hour / week


  • Number of words: 500+
  • Duration: 10 weeks or less
  • Time: 1 hour / week


  • Number of words: 700+
  • Duration: 10 weeks
  • Time: 1 hour / week