glass

I. mir‧ror1 S3 W3 /ˈmɪrə $ -ər/ noun [countable]
[Date: 1200-1300; Language: Old French; Origin: mirour, from mirer 'to look at', from Latin mirare]
1. a piece of special glass that you can look at and see yourself in
  in a mirror
   • She was studying her reflection in the mirror.
   • He spends hours in front of the mirror!
   • When I looked in the mirror I couldn’t believe it. I looked fantastic!
2.
   a mirror on the inside or side of a vehicle, which the driver uses to see what is behind:
   • Check your rear-view mirror before you drive away.
   • a wing mirror
3. a mirror of something something that gives a clear idea of what something else is like SYN reflection:
   • We believe the polls are an accurate mirror of public opinion.

Oxford Advanced Learner's Dictionary

mirror

mir·ror [mirror mirrors mirrored mirroring] noun, verb [ˈmɪrə(r)] [ˈmɪrər]

noun

1. countable a piece of special flat glass that reflects images, so that you can see yourself when you look in it

• He looked at himself in the mirror.

• a rear-view mirror (= in a car, so that the driver can see what is behind)

• (BrE) a wing mirror (= on the side of a car)

• (NAmE) a side-view mirror

2. a ~ of sth singular something that shows what sth else is like

• The face is the mirror of the soul.

• Dickens' novels are a mirror of his times.

Word Origin:

Middle English: from Old French mirour, based on Latin mirare ‘look at’. Early senses also included ‘a crystal used in magic’ and ‘a person deserving imitation’.

Example Bank:

• Art can be seen as a mirror image of society.

• He was busy admiring himself in the mirror.

• He watched them through a two-way mirror.

• She stared at her face in the mirror.

• We hung a mirror over the fireplace.

• a large mirror hanging on the wall behind him

Cambridge Advanced Learner's Dictionary

Cambridge Advanced Learner's Dictionary - 4th Edition

mirror / ˈmɪr.ə r / / -ɚ / noun [ C ] (GLASS)

A2 a piece of glass with a shiny, metal-covered back that reflects light, producing an image of whatever is in front of it:

the bathroom mirror

She was looking at her reflection in the mirror.

mirror / ˈmɪr.ə r / / -ɚ / noun (REPRESENT)

be a mirror of sth to represent or show something honestly:

The movie is a mirror of daily life in wartime Britain.

Collins COBUILD Advanced Learner’s English Dictionary

mirror

/mɪrə(r)/
(mirrors, mirroring, mirrored)

Frequency: The word is one of the 3000 most common words in English.

1.
A mirror is a flat piece of glass which reflects light, so that when you look at it you can see yourself reflected in it.
He absent-mindedly looked at himself in the mirror...
N-COUNT
• mir‧rored
...a mirrored ceiling.
ADJ

2.
If something mirrors something else, it has similar features to it, and therefore seems like a copy or representation of it.
The book inevitably mirrors my own interests and experiences...
= reflect
VERB: V n

3.
If you see something reflected in water, you can say that the water mirrors it. (LITERARY)
...the sudden glitter where a newly-flooded field mirrors the sky...
= reflect
VERB: V n

Merriam-Webster's Advanced Learner's Dictionary

Merriam-Webster's Advanced Learner's Dictionary:

¹mir·ror /ˈmirɚ/ noun, pl -rors [count]
1 : a piece of glass that reflects images
• She saw her reflection in the mirror. = She looked at herself in the mirror.
• a bathroom mirror
- see pictures at bathroom, car; see also rearview mirror
2 : something that shows what another thing is like in a very clear and accurate way - usually singular
• Her art is a mirror of modern American culture.