A test tube is a piece of cylindrical glassware that has numerous applications in laboratories and scientific experiments. Sometimes, it becomes crucial to use synonyms for the word "test tube" to avoid repetition and make the text more interesting. Some of the synonyms for the term "test tube" include a culture tube, sample tube, reaction tube, assay tube, and a specimen tube. A culture tube is generally used to grow bacteria, viruses, or fungi; a sample tube is used to keep small amounts of liquids and gases for analytical purposes, while a reaction tube is used to watch chemical reactions. An assay tube and a specimen tube are used to analyze blood samples and tissue samples, respectively. Overall, these synonyms can help make your text more fluent and engaging.