Theoretically

Theoretically is an adverb meaning in theory or according to a theory or model, rather than in practice. It signals that a statement follows from a set of assumptions, definitions, or formal structures, not from direct observation or real-world results. The word is built from the noun theory with the suffix -ly and has been in English since at least the early modern period.

In science, philosophy, and related fields, theoretically describes what would occur under idealized conditions or within a specific theoretical framework. Theoretical conclusions are derived from models, axioms, or logical deduction and may or may not be borne out by experimentation or experience. Theoretical work often guides inquiry by outlining possibilities, while empirical work tests those possibilities in the real world. The distinction between theoretical and practical considerations is a common point of emphasis in disciplines such as physics, economics, and computer science.

Usage notes and common phrases include "theoretically speaking," "theoretically possible," and "in theory." The term is frequently contrasted with practical feasibility or experimental verification. A statement may be theoretically valid yet impractical due to technical limits, cost, or uncontrolled variables. Thus, while theories can provide powerful predictions, real-world constraints can alter or invalidate those predictions.