- 百日咳 bǎirìké whooping coughpertussis; an acute infectious disease, usually affecting young children, characterized by long-lasting fits of convulsive coughing
- 一日夫妻百日恩 yīrìfūqībǎirì'ēn once husband and wife, always in loveOnce a couple has been husband and wife for even a single day, they will have deep and lasting affection for each other forever.
- 百日维新 bǎirìwéixīn Hundred Days of ReformA failed attempt at political and social reform in late 1898 under the Qing dynasty, lasting 103 days before it was suppressed by Empress Dowager Cixi and the conservative faction; also known as the [[戊戌变法|戊戌變法|wu4 xu1 bian4 fa3]].
- 花无百日红 huāwúbǎirìhóng good times don't last longno flower blooms for a hundred days; used to describe how youth fades quickly or how good fortune is temporary
- 百日红 bǎirìhóng crape myrtlethe crape myrtle tree or its flowers; also known as [[紫薇|紫薇|zi3 wei1]]
- 百日菊 bǎirìjú zinniazinnia; common garden plant of the daisy family