What is the meaning of ''everglow''?

Coldplay use this word in their new song Everglow. Some people on the internet do too. However, I can't find the meaning of this word in the dictionary.

Does this word actually exist? If so, what is its meaning?

Solution 1:

ever- can be used as a prefix having the sense of "always" or "continuously". (E.g. Macmillan online]

Short of a formal definition, you can assume that "everglow" carries the sense of glowing always or continuously.

From the song itself:

There's a light that you give me/ When I'm in shadows /It's a feeling within me, everglow.

… the light that you left me will everglow …

The sense seems to be that the "light" bestowed upon the narrator by the beloved will glow forever.