noun

boundary

boundary, border, limit

The river forms a natural boundary.

The river forms a natural boundary.

He has no sense of personal boundaries.

He has no sense of personal boundaries.

((a/the)) boundary ((between sth. and sth.)) a line that marks the limits of an area The fence marks the boundary between our properties.

((a/the)) boundary ((of sth.)) the limit of something We are pushing the boundaries of science.

Synonyms: border, limit, frontier; Antonyms: centre, interior

From 'bound' (limit) + '-ary' (related to). Literally 'relating to a bound'.

Think of a line that 'bounds' or contains an area. It's the outer limit.

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