A person who is not quite a friend yet but more than an acquaintance. You take part in light-hearted chat and would most probably only talk to them if you were with a group of people; the same goes for hanging out with them. You also might say Hi to them when meeting in the street, but you wouldn't stop and chat.
Gary: Hmmm... I'm not sure if I can ask him yet, we're really only social-colleagues at the moment. Ask Kyle though, he was at friend level last time I checked.
A workplace cohort who has taken it upon herself to take on the role of a nightmare sister, finding ways to endlessly embarrass, harass, prank and annoy you to the point of near-insanity.
When I wake up some mornings I find myself breaking out in a cold sweat just imagining the weird and unexpected things my nightmare sister colleague might do to me that day.
Fred: So what are you doing this weekend?
Jane: ah, you know just meeting up with my friends and doing other cool stuff with my friends.. so ya I will see you on Monday.. at work.
Sort of a lovely nickname used between British actor/writer Stephen Fry and Hugh Laurie
Can be abbreviated as "m'coll"
And you can use the word "y'coll" when refering one of them to the other(as the short form of "your colleague", obviously)
"M'colleague has noticed that, besides the usual court circular of saints, battles, dance craze etc, today is the 30th anniversary of Jeeves and Wooster. I wish him, and anyone who enjoyed it half as much as we did, tinkerty tonk." ——Hugh Laurie on Twitter, 4/23/2020