内 means “inside, within”

ない · nai

Also: between, among

Kun'yomi (Japanese reading)
うち
On'yomi (Chinese reading)
ナイ, ダイ

JLPT N3 · Taught in grade 2 · 4 strokes

The story

A person (人) stepping in under a roof (冂): inside. 内 marks what's within: 国内線 are domestic flights, 案内 is the guidance at an information desk, and 3日以内 means within three days.

Used in 案内 (annai, guidance), 内容 (naiyou, contents), and 以内 (inai, within)

More from Ties & Differences

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Readings from KANJIDIC2, © EDRDG, CC BY-SA.