This document defines medical terminology prefixes and suffixes used in diagnosis. Some key terms summarized are: - Assay, meter, and metry refer to tests, instruments, and measurements. Examples include spirometer and pelvimetry. - Scope and scopy refer to lenses and endoscopic examinations. Examples include stethoscope, gastroscope, and laparoscopy. - Gram refers to pictures or images, such as electrocardiograms. - Graph refers to recorders and descriptions of measurements, such as electrocardiographs and angiography. - Tomy refers to cross-sections, such as in tomography, laminography, and computed tomography scans.