- 四角形 sìjiǎoxíng quadrilateral(geometry) quadrangle; quadrilateral
- 四角号码 sìjiǎohàomǎ four-corner codefour corner code (input method for Chinese characters)
- 四角柱体 sìjiǎozhùtǐ cuboida solid geometric figure with six rectangular faces, also known as a rectangular prism
- 四角裤 sìjiǎokù boxersboxer shorts