1. Connected with or lying on the border.

2. The confines or extreme part of a country bordering on another country.

Nuttall's Standard dictionary of the English language By Nuttall, P.Austin

• fontier,
• fronteer,
• frontire,
• frontieer,
• frontge,
• frotier,
• frontfor,
• pronter,
• fonteer,
• froniter,
• fronteir,
• fropntier,
• fronter,
• frounteer,
• fromteer,
• fronier,
• frontiere,
• frointier,
• rontier,
• afrontive

• front line,
• frontage,
• front-stall,
• frontal,
• front crawl,
• Frint,
• frontlet,
• front room,
• frontmost,
• frenette,
• Fronted,
• Fronting,
• front door,
• frantic,
• frontwards,
• front porch,
• front bench,
• front,
• frontward,
• frostier,
• frenetic,
• front yard.

The adjective form of the word "frontier" is "frontier". The word can be used as a noun or an adjective without any change in form. For example, "frontier town" or "frontier region".

The plural of the "frontier" can be the "frontiers".

The singular of the "frontier" can be the "frontier".