De cubitus is a Latin phrase that means lying down or reclining. There are several synonyms that can be used to convey the same meaning, such as recumbent, prone, supine, horizontal, prostrate, and reclined. All of these words describe a position in which the body is resting in a relaxed manner with the back on a flat surface. These synonyms are commonly used in medical literature, especially when referring to a patient's position during surgery or treatment. It is important to note that some of these synonyms may have slightly different connotations depending on the context, so it is always advisable to use the most appropriate word for the situation.