1.
inside and outside
Both the interior and exterior of something.
2.
domestic and foreign; home and abroad
Both within a country and internationally.
3.
approximately
About (a certain number); roughly.
内外 combines 内 (inside) + 外 (outside), with three distinct uses.
MEANINGS:
1. Inside and outside (physical): 建物の内外
2. Domestic and foreign: 国内外
3. Approximately (with numbers): 100人内外
COMMON EXPRESSIONS:
- 国内外: domestic and international
- 社内外: inside and outside the company
- 内外の情勢: domestic and international conditions
- 〜内外: approximately (formal register)
NOTE ON "APPROXIMATELY":
The "approximately" meaning is more formal than 約 or ぐらい. Often seen in news and business contexts.