“energy efficiency”

We have one entry that includes the term energy efficiency.

energy efficiency ratio

noun, often capitalized both Es&R

: a number expressing the relative efficiency of an appliance (such as a room airconditioner) that is obtained by dividing the unit's output in BTUs per hour by its energy requirement in watts

See the full definition

Word of the Day

Listen to the pronunciation of hobgoblin

See Definitions and Examples »

Test Your Vocabulary

Commonly Confused Words Quiz

  • vector image of a face with thought expression
  • I went to the ______ store to buy a birthday card.
Spell It

Hear a word and type it out. How many can you get right?

TAKE THE QUIZ
Play Blossom: Solve today's spelling word game by finding as many words as you can using just 7 letters. Longer words score more points.

Pick the best words!

PLAY
Love words? Need even more definitions?

Subscribe to America's largest dictionary and get thousands more definitions and advanced search—ad free!

Games & Quizzes

See All
Play Quordle: Guess all four words in a limited number of tries. Each of your guesses must be a real 5-letter word.
Quordle Can you solve 4 words at once?
Play Blossom: Solve today's spelling word game by finding as many words as you can using just 7 letters. Longer words score more points.
Blossom Pick the best words!
Play Missing Letter: a crossword with a twist. Each of the 25 puzzle words start with a different letter of the alphabet. Which letter is missing?
The Missing Letter A daily crossword with a twist
pastel colored puzzle piece speech bubbles with shadows
Quiz: Find the Missing Link Figure out the word that fits both halves of the ...
See All