是否 (shì fǒu) means “whether (or not); if; is or isn't”. It is an HSK 4 Chinese word in the HSK 3.0 vocabulary.
Practice each character:
我不确定他是否会来。
Wǒ bù quèdìng tā shìfǒu huì lái.
I'm not sure whether he will come.
Updated: 2026-05-27