Natural parent is a term often used to describe a biological or birth parent. However, there are several other synonyms that can be used instead of using the phrase "natural parent." Some common alternatives include birth parent, biological parent, genetic parent, and biological mother/father. These terms are more specific and describe the biological connection between the parent and child. Other relevant terms may include legal parent, adoptive parent, step-parent, and foster parent. Each of these terms describes a different type of parental relationship and can help to clarify the nature of the connection between the parent and child.