How would you define/explain/describe emotional adultery?

What do you think it is?

I'd like to see what others say before swaying the conversation by saying what is going on

adultery is when you are married ( not fooling around with this thing called dating/boyfriend/girlfriend/etc ), and you have intercourse with somebody outside your marriage that was not part of the agreement.

Reality marriage is a business plan. From the start both parties have to understand the means of this marriage. Sometimes people marries for "love" which was a new invention, other times they think it is a religious spiritual thing. You have...

Non-monogamous relationships
Power couples

Some people get married just to show boat they are normal and have somebody to appear before their parents or employment.

You are the one who defines what's acceptable or not.
Some men watch porn day-in and day-out and personally I don't think it's adultery, but some wives do. I do think these men have a psychological problem, but that's another topic.
Some men have romantic relationship with a woman either through social media or phone. Again, the only person who can determine how intimate it is, would be you.
If my husband would flirt, engage with another woman online or via phone, I would ask myself first why? Am I so boring, is the marriage too set in its ways,
have I neglected him etc. etc.

Obviously you talked about it as he sees it differently than you do. Why don't you look for interests you can pursue without him? Spend a weekend with your girlfriends, go hiking with a group, just do your own thing and see if he minds.

If he is not the least bit interested what you're doing then you have bigger problems than his emotional absence. You should opt for counseling regardless.

Do you mean your husband is having an emotional affair?

That is when the devotion, attention, financial support and time is given to another person instead of the spouse.