<p><strong>Adjective</strong></p><ul><li>not changing or varying; uniform; regular; invariable: All conditions during the three experiments were constant.</li><li><strong>Synonyms:</strong> permanent, immutable</li><li><strong>Antonyms:</strong> changeable</li><li>continuing without pause or letup; unceasing: constant noise.</li><li><strong>Synonyms:</strong> unremitting, perpetual</li><li><strong>Antonyms:</strong> fitful</li><li>regularly recurrent; continual; persistent: He found it impossible to work with constant interruption.</li><li><strong>Synonyms:</strong> ceaseless, incessant</li><li><strong>Antonyms:</strong> sporadic</li><li>faithful; unswerving in love, devotion, etc.: a constant lover.</li><li><strong>Synonyms:</strong> true, staunch, loyal</li><li><strong>Antonyms:</strong> unreliable</li><li>steadfast; firm in mind or purpose; resolute.</li><li><strong>Synonyms:</strong> steady</li><li>Obsolete: certain; confident.</li></ul><p><strong>Noun</strong></p><ul><li>something that does not or cannot change or vary.</li><li>Physics: a number expressing a property, quantity, or relation that remains unchanged under specified conditions.</li><li>Mathematics: a quantity assumed to be unchanged throughout a given discussion.</li></ul>