When we keep our emotions, thoughts or feelings to ourselves instead of expressing them, we may be said to be "bottling up." This may lead to a build-up of tension, anxiety or depression. Synonyms for this phrase can also include internalizing, suppressing, stifling, concealing, repressing, holding back, or suppressing. All of these phrases describe the act of not sharing our thoughts, feelings, or emotions with others. Bottling up can be detrimental to our mental and physical health, as it can cause stress and tension to build up over time. It's important to learn healthy coping mechanisms to help express ourselves and deal with our emotions in a constructive way.