I've perused many sites and have found "コ上," but if I hit translate, I get "co-on," a term I am not familiar with. Is this a Japanese term with no English equivalent?

I'm attempting to read a manga and this phrase pops up twice and has me completely baffled. Below are the contexts in which I found them. Any help would be much appreciated.

オレらより１コ上なんだけど
海外行ってる間の
単位取得で

and

１コ上の先輩に聞いたんだけど
留学先で仲間と会社設立して
そんごい儲けたんだって