I found the following sentence in an article:
Chaaya becomes very happy when she finds that her son is still alive. Her eyes well up.
What is the meaning of "eyes well up"? I tried to check this in the Oxford dictionary, but there I found a close meaning:
‘tears were beginning to well up in her eyes’
But I nowhere found "eyes well up" in any of these 3 dictionaries: Oxford, Cambridge, Merriam-webster. I also checked this through Google ngram and found that this is commonly used nowadays. I am not able to understand whether this combination of words "eyes well up" has any meaning?