I can remember the days when a friend was someone you met for coffee before work. Someone you called when had good news or bad news or anything in between. Someone who made you laugh and sometimes cry and someone who you knew had your back when times were tough.

These days, a friend is someone who "liked" the same online article you did. Or someone who is a friend-of-a-friend-of-a-friend-of someone you know. Or anyone at anytime you went to school with or worked with or rode a bus with.

Given this promiscuity when it comes to friendships, it's no wonder that we seem to have lost the ability to know how to have a friend and be a friend. According to a new study, more than half of the people we consider friends don't see us the same way.

The study, which was conducted by researchers at Tel Aviv University and the Massachusetts Institute of Technology and published in the journal PLOS One, asked college students from the same class to rate each other on a scale of one to five with "1" defined as "I don't know this person" and "5" indicating the person is a best friend. On this scale, "3" was considered the base level of friendship. Participants also evaluated how they thought the other person viewed them.

Researchers ranked 1,353 instances of friendship in which at least one person ranked the other as a "3" or higher. In 94 percent of those cases, the participant thought the other person felt the same way about them. But sadly, this was true only about half the time.

A few things here to keep in mind: For starters, this research is based on a very small sample size of just 84 students. It's hard to know if one can truly draw conclusions about friendships based on a handful of college students.

Also, the definitions used within this study were incredibly vague. So the perception of friendship could be different simply because one person has a different definition of "friendship" than another. If I sit next to the same kid in class and chit chat with him everyday, I might consider him a friend, whereas he might reserve that term for the peers he hangs out with after class. The difference is one of semantics.

However, the other issue to consider is the aforementioned way we actually define friendships in the age of social media. In the world of clicks and likes, it's entirely possible the very definition of friendship has become ambiguous. And we have lost the social cues needed to understand how to be — and spot — a true friend.

Now that's depressing. And it might mean it's time to take a closer look at your "friend" list and find someone on there you can meet for a cup of coffee.