Dictionary.net

an undeveloped field of study; a topic inviting research and development; "he worked at the frontier of brain science"

an international boundary or the area (often fortified) immediately inside the boundary

an undeveloped field of study; a topic inviting research and development; "he worked at the frontier of brain science"

an international boundary or the area (often fortified) immediately inside the boundary

on the American frontier; "one of the last real frontier towns"; "hardships of frontier life"

That part of a country which fronts or faces another country or an unsettled region; the marches; the border, confine, or extreme part of a country, bordering on another country; the border of the settled and cultivated part of a country; as, the frontier of civilization.

An outwork.

Lying on the exterior part; bordering; conterminous; as, a frontier town.

To constitute or form a frontier; to have a frontier; - with on.

That part of a country which fronts or faces another country or an unsettled region; the marches; the border, confine, or extreme part of a country, bordering on another country; the border of the settled and cultivated part of a country; as, the frontier of civilization.

An outwork.

Lying on the exterior part; bordering; conterminous; as, a frontier town.

To constitute or form a frontier; to have a frontier; - with on.

The boundary or limit of a country; the most remote settled part of a country, facing an unexplored region.

Pertaining to, or situated near, the boundary of a country.

That part of a country which fronts or faces another country; the confines or extreme part of a country bordering on another country; the marches; the border: a fort; a fortification; "Of pallisadoes, frontiers, parapets."-Shak.: the forehead; "Then on the edges of their bolster'd hair, which standeth crested round their frontiers, and hangeth over their faces."-Stubbes.

Of or pertaining to, or acquired on a frontier: lying on the exterior part: bordering: conterminous; as, a frontier town. "Frontier experience."- IV. Irving. "They thus remained till new dangers made it expedient for Russia to reassemble them, and she formed a frontier militia of their tribes."-Brougham.

To form or constitute a frontier to possess territories bordering on or constituting a frontier-with on or upon.

To place on the frontier: to guard or invest on the frontier. "Now that it is no more a border nor frontiered with enemies."-Spenser.

Boundary of a country.

The border of a country; the confines of civilization.

n. [Latin] That part of a country which fronts or faces another country; the marches; the bolder; the outmost limit or verge.

The marches, the limit, the utmost verge of any territory.

Bordering.