<p><strong>Noun</strong></p><ul><li>Informal. An excessive estimate of one's importance; conceit.</li><li>Veterinary Pathology. An inflammatory swelling of the tissues of the heads of sheep, caused by the anaerobic bacillus <em>Clostridium novyi</em>.</li><li>Enlargement of the heads and jawbones of horses resulting from nutritional hyperthyroidism.</li></ul>