"Gaining on" is a phrase that denotes a sense of catching up or progress made towards a specific goal. Synonyms for this term include closing in on, approaching, getting nearer to, advancing towards, and making headway. Other possible options are moving in on, pressing forward, nearing, and drawing closer to. These descriptive words can be used interchangeably with "gaining on" to signify forward movement, increasing proximity, and the achievement of objectives. Whether it's running towards a finish line or reaching a destination, using these synonyms can add variety and depth to your language, helping you to convey a more specific and nuanced message.