Real Dictionary

reflection
countable noun: A reflection is an image that you can see in a mirror or in glass or water.
countable noun: If you say that something is a reflection of a particular person's attitude or of a situation, you mean that it is caused by that attitude or situation and therefore reveals something about it.
singular noun: If something is a reflection or a sad reflection on a person or thing, it gives a bad impression of them.
uncountable noun: Reflection is the process by which light and heat are sent back from a surface and do not pass through it.
variable noun: Reflection is careful thought about a particular subject. Your reflections are your thoughts about a particular subject.

reflection in American English
a reflecting or being reflected
noun: the act of reflecting or the state of being reflected

reflection in British English
noun: the act of reflecting or the state of being reflected

reflection in Chemical Engineering
noun: Reflection is when infrared waves (= waves with a longer distance between them than waves of visible light) bounce from a surface.