Excessively means much more than is reasonable or necessary — not just “a lot,” but too much. If someone worries excessively, the worrying has gone past what the situation needs. If food is excessively salty, there is more salt than most people would call all right. The word almost always carries a small frown: it judges the amount as over the line. You will hear it in careful speech and writing (“excessively expensive,” “excessively long”), and it can describe feelings, habits, or physical amounts. Though actually, people sometimes use it with a dry smile, as a polite way of saying “ ridiculously”: “He is excessively proud of that hat.” The core is still “more than it should be.”