Threpsis is a technical term, from the Greek threpsis meaning nourishment, for nutrition — the process by which organisms take in and use food. It belongs to the classical vocabulary of physiology and medicine, where it appears in compound terms describing nutritional states and processes. While modern nutrition science uses plainer language, threpsis survives in specialist terminology and in the roots of words such as threpsology. The concept it names is the foundation of the field: the sum of the processes — ingestion, digestion, absorption, metabolism — by which food becomes the energy and structure of the living body. Good threpsis is simply good nutrition by another name.