Creode or chreod is a neologistic portmanteau term coined by the English 20th century biologist C. H. Waddington to represent the developmental pathway followed by a cell as it grows to form part of a specialized organ.[1] Combining the Greek roots for "necessary" and "path," the term was inspired by the property of regulation.[2] When development is disturbed by external forces, the embryo attempts to regulate its growth and differentiation by returning to its normal developmental trajectory.