Meaning of the word frontier in English

What does frontier mean in English? Explore the meaning, pronunciation, and specific usage of this word with Lingoland.

frontier

US /frʌnˈtɪr/
UK /ˈfrʌn.tɪər/

Noun

1.

a line or border separating two countries

Example:
The soldiers guarded the frontier between the two nations.
They crossed the frontier illegally.
2.

the extreme limit of settled land beyond which lies wilderness, especially in reference to the western US before the 20th century

Example:
Pioneers ventured into the vast American frontier.
Life on the frontier was harsh and challenging.
3.

the extreme limit of understanding or achievement in an area of knowledge or endeavor

Example:
Space exploration represents the ultimate frontier of human endeavor.
Scientists are pushing the frontiers of medical knowledge.