<p><strong>Noun</strong></p><ul><li>a person or thing that helps or gives assistance, support, etc.</li><li>an extra locomotive attached to a train at the front, middle, or rear, especially to provide extra power for climbing a steep grade.</li></ul><p><strong>Synonyms</strong></p><ul><li>ally</li><li>auxiliary</li><li>backer</li><li>supporter</li><li>assistant</li><li>aid</li></ul>