undefined
adj.adj. not having a clear meaning, limit, or description. In math or computer code, it describes something that has no value or has not been explained yet.
adj. lacking a precise explanation, boundary, or definition. In technical contexts, it refers to a variable or expression that has not been assigned a value or whose value is mathematically impossible to determine.
The rules of the game remain undefined for now.
The program crashed because it tried to access an undefined variable that had no data assigned to it.
While the legal framework for the new territory is still largely undefined, local authorities are operating under a temporary set of guidelines to maintain order.
From un- + defined.
Etymology adapted from Wiktionary, available under CC BY-SA 4.0.
Often follows a linking verb like 'be', 'remain', or 'stay'. In computing, it is frequently used as a technical state rather than just a descriptive quality.
Last updated May 11, 2026