- 北回归线 běihuíguīxiàn Tropic of CancerThe circle of latitude approximately 23.5 degrees north of the equator where the sun is directly overhead at the summer solstice
- 南回归线 nánhuíguīxiàn Tropic of CapricornThe southern line of latitude (approximately 23.5°S) that marks the farthest south the sun can be directly overhead.
- 回归线 huíguīxiàn tropicOne of the two latitude lines on Earth representing the farthest north or south where the sun can be directly overhead; refers to the [[北回归线|北回歸線|bei3 hui2 gui1 xian4]] or the [[南回归线|南回歸線|nan2 hui2 gui1 xian4]].
- 回归年 huíguīnián solar yearThe time required for the Earth to complete one orbit around the Sun measured between successive equinoxes; also called a tropical year.
- 回归热 huíguīrè relapsing feveran acute infectious disease characterized by high fever, headaches, and liver or spleen enlargement, where symptoms disappear after about a week only to recur several recur several times; also called recurring fever
- 线性回归 xiànxìnghuíguī linear regressionA statistical method used to model the relationship between a dependent variable and one or more independent variables.
- 回归分析 huíguīfēnxī regression analysisregression analysis; a statistical method for estimating the relationship between variables
- 回归带 huíguīdài the tropicsThe area of the Earth's surface between the Tropic of Cancer and the Tropic of Capricorn; also known as the [[热带|熱帶|re4 dai4]].