1One of two equal parts of something — half of a whole. As a prefix (半〜), it can also mean "partial" or "semi-."
リンゴを半分に切って分けよう。
Let's cut the apple in half and share it.
会議はまだ半分しか終わっていない。
The meeting is only half finished.
このセーターは半袖に作り直せそうだ。
This sweater could probably be remade into a half-sleeve (short-sleeve) one.
半信半疑でその話を聞いていた。
I listened to that story half in doubt.
2Used in the form "~o'clock half" to indicate 30 minutes past that hour.
授業は9時半に始まる。
Class starts at 9:30.
夜7時半に駅で待ち合わせしよう。
Let's meet at the station at 7:30 in the evening.
いつも12時半に昼ご飯を食べる。
I always eat lunch at 12:30.
3In the traditional dice game "chō-han," this refers to the total of the dice being an odd number.
サイコロの目の合計が奇数なら「半」、偶数なら「丁」と呼ばれる。
If the total of the dice is odd it's called "han," and if even it's called "chō."
4An archaic unit of land area; almost never used in modern Japanese.