<p><strong>Noun</strong></p><ul><li>the act of replacing.</li><li>a person or thing that replaces another:<ul><li>summer replacements for vacationing staff.</li><li>a replacement for a broken dish.</li></ul></li><li>Military: a sailor, soldier, or airman assigned to fill a vacancy in a military unit.</li><li>Also called metasomatism.</li><li>Geology: the process of practically simultaneous removal and deposition by which a new mineral grows in the body of an old one.</li></ul>