<p><strong>Noun</strong></p><ul><li>A single-minded person obsessed with a hobby or pursuit or with a particular topic.</li><li>A person considered to be socially awkward, boring, unstylish, etc.</li></ul><p><strong>Verb</strong></p><ul><li>(used without object) to spend inordinate amounts of time, attention, energy, enthusiasm, etc., on an activity or topic of special interest to oneself.</li><li>To engage with excessive enthusiasm in a hobby or in discussion about a topic of special interest to oneself.</li><li>To alter or be altered in a way that shows excessive enthusiasm for a special interest.</li></ul>