<p><strong>Noun:</strong></p><ul><li>A person sentenced to or serving a term of life imprisonment.</li><li>A person committed to a professional lifetime career in the military.</li><li>A person who has devoted a lifetime to a profession, occupation, or pursuit.</li><li>(In birding) Also called life bird; a species of bird not seen previously and that will therefore be added to the bird watcher's life list.</li><li>The sighting of a bird of a previously unseen species.</li></ul>