If a reason, argument, or explanation is cogent, it is clear, well ordered, and it pulls you toward agreeing. It does not only “sound nice.” It fits the facts and moves step by step, so you think, “Yes, that holds.” People use this word in careful writing, law, and school essays, not much in everyday chat. You might hear a teacher say “a cogent point.” Though actually, some writers stretch it to mean little more than “convincing” or even “good,” without that sense of tight reasoning. A loud speech can still fail to be cogent; a quiet, careful case can succeed. The word is almost always about ideas, not about people. Calling a person cogent sounds odd; calling their case cogent is the usual way.