1. To share or divvy up something with one. In this usage, a noun or pronoun is used between "split" and "with." The portions are really huge here, so I'm just going to split an entrée with Mary. He agreed to split the earnings evenly with his partner.

2. To end a romantic relationship with one. I heard you split with your boyfriend—I'm so sorry to hear that! Martin says that he split with Sarah, but they've had such an on-again-off-again relationship that none of us is surprised anymore.