Today I had lunch with a cousin who is also interested in the family tree. To be precise, he is my second cousin. That is one of those relationships which has the same label both ways around and is irrespective of gender, unlike aunt and niece, uncle and nephew. He is my second cousin and I am his second cousin, we are second cousins.
You may use a computer software program which labels each person on file according to their relationship to you. Alternatively you can use, for example in tea towel form, The Cousin Explainer:
One advantage of the computer program over the tea towel is the option to easily find the relationship between any two other people in your family tree. Another benefit is that the computer copes with a wider range of relationships.
The software that I use can produce a "Kinship Report" and it can be sorted so that the closest relationships are listed first. Amongst the more distant relatives that I have on file are a "wife of second cousin three times removed" and a "wife of half third great uncle".
Nearly one-quarter of the people in my family tree file are actually tagged as being unrelated to me. These include extended families with my surname but without any ancestor identified as being in common with me, yet. Also, I keep track of individuals and families who appear with different surnames in different records (see McQuay name variants).
You might interpret this as thorough record-keeping for the one-name study approach. Alternatively, you may decide this looks like a family historian who is stuck and desperately searching for clues and extra pieces of the puzzle as part of sleuthing for cousins.