棟

Literal: The primary horizontal support of a building, specifically the ridgepole or main beams.

Metaphorical: A mainstay; an indispensable person of talent or moral weight who supports a state, family, or institution (often appearing in the compound 棟樑).

Noun: Standard usage referring to either the physical beam or the metaphorical pillar.

Classifier: In later imperial texts, functions as a measure word for buildings.

Contrast with 柱 (vertical pillar) and 樑 (general beam). While 樑 is a broad term for any supporting beam, 棟 typically denotes the central, crowning member of the roof structure.

Simplified variant: U+680B.

Determine if the context is architectural or social. In literal contexts, 棟 indicates the most critical point of stability or failure in a roof's construction. In political or familial contexts, it almost certainly refers to an indispensable individual.