The phrase "to a certain degree" can be used to express a certain level of uncertainty, rough estimation or approximation. However, in order to sound more articulate and avoid repetitive usage of the phrase, there are various synonyms that can be used. For instance, one can use the phrase "to some extent" or "to some degree" to communicate a similar meaning. Alternatively, "partially" or "in part" can work well to convey the idea of being partly true or valid. "To a limited extent" is also a good option to show a certain level of restriction or boundary. Ultimately, these synonyms can help improve communication and convey more accurate information.