to press a contention against another: to quarrel, take someone to task, or argue a case against them
At its core this word names one party setting itself against another and pushing a grievance: someone has a complaint and presses it. The same verb covers the whole range of how that gets done, from a shouting match at a well to a carefully argued case before a judge, because Hebrew sees these as one activity at different volumes. What never changes is that two sides are locked in conflict and one is making its charge stick.
The two senses below are not two different words but two settings for the one act. In ordinary life it is a quarrel or a falling-out, neighbors fighting over water or wages, a crowd turning on its leader. In the courtroom (and in the prophets, who picture God taking his people to court) the very same pressing of a complaint becomes pleading a case, accusing, demanding a hearing, or defending the helpless whose cause no one else will take up.
Because both senses sit so close together, many verses could be heard either way, and the line between a hot argument and a formal charge is often exactly the point a passage is making. The word lets a private quarrel and a legal accusation share a single name, which is why it can move from Isaac's herdsmen to the courtroom of God without ever changing its meaning.