longitudinal
adjective specialized uk/ˌlɒŋ.ɡɪˈtʃuː.dɪ.nəl/ uk/ˌlɒn.dʒɪˈtʃuː.dɪ.nəl/ us/ˌlɑːn.dʒəˈtuː.dɪ.nəl/
经线的
used to refer to lines or distances east or west of an imaginary line between the North Pole and the South Pole
Longitudinal lines run from north to south. 经线的方向是由北至南。
medical （身体或身体部分）纵向的
in the long direction of the body or of any body part
a longitudinal rash 纵向皮疹
medical, social sciences 纵向研究，纵贯研究
Longitudinal research is done on people or groups over a long period of time.
longitudinal analysis/studies 纵向分析／研究