Final answer:
The combining form "hist/o" in medical terminology refers to tissues, associated with the study of histology, the shape and arrangement of cells in tissue.
Step-by-step explanation:
In medical terminology, the combining form "hist/o" typically refers to tissues. Specifically, it is used in the context of histology, which is the scientific study of the shape and arrangement of cells in tissue. Histology is a fundamental field in medicine and biology, as it provides significant insights into the detailed microscopic structures of tissues, which are vital to understanding both normal physiology and pathology. Cells and tissues originate from three primary germ layers in the developing embryo known as the ectoderm, mesoderm, and endoderm. These layers give rise to all the varied tissues in the body.