Collins Chinese Dictionary Plus (3rd edition), 2011:
多半 duōbàn
I 数
- 这(這)个(個)班的学(學)生多半英语(語)好。 Zhège bān de xuéshēng duōbàn Yīngyǔ hǎo. Most of the students in this class have good English.
- 他的家庭成员(員)多半赞(贊)同他的婚事。 Tā de jiātíng chéngyuán duōbàn zàntóng tā de hūnshì. On the whole, most of his family were happy about his marriage.
II 副 (=大概) very likely
- 今天多半要下雨。 Jīntiān duōbàn yào xiàyǔ. It's very likely to rain today.