powerless

Concise Oxford English Dictionary © 2008 Oxford University Press:
power/ˈpaʊə(r)/

▶noun

• 1 the ability to do something or act in a particular way.

• 2 the capacity to influence the behaviour of others, the emotions, or the course of events.

• 3 a right or authority given or delegated to a person or body.

  ■ political authority or control.

  ■ [as modifier] informal denoting something that is associated with people who are influential in business or politics: power dressing.

• 4 a country viewed in terms of its international influence and military strength: a world power.

• 5 physical strength or force.

  ■ capacity or performance of an engine or other device.

  ■ the magnifying capacity of a lens.

• 6 energy that is produced by mechanical, electrical, or other means.

  ■ [as modifier] driven by such energy: a power drill.

• 7 Physics the rate of doing work, measured in watts or horse power.

• 8 Mathematics the product obtained when a number is multiplied by itself a certain number of times.

▶verb

• 1 supply with power.

  ■ (power something up/down) switch an electrically powered device on or off.

• 2 move or cause to move with speed or force: he powered round a bend.

– phrases
do someone a power of good informal be very beneficial to someone.
the powers that be the authorities. [with biblical allusion to Rom. 13:1.]

– derivatives
powered adjective,
powerless adjective,
powerlessly adverb,
powerlessness noun.

– origin ME: from Anglo-Norman Fr. poeir, from an alt. of L. posse ‘be able’.