IPA: /ˌɪn.təˈsteɪ.di.əl/
KK: /ɪnˈtɜr.steɪ.di.əl/
Relating to a temporary warming period that occurs during an ice age, when ice melts and temperatures rise for a time.
The interstadial period allowed for the growth of vegetation in areas that were otherwise covered in ice.
A period of time during which there is a temporary warming between two glacial periods, characterized by a retreat of ice.
The interstadial allowed for the growth of vegetation in areas that were previously covered by ice.
Interstadial is formed from "inter-" (meaning between) and "stadium" (from Latin "stadium", meaning a standing or phase). The term refers to a period that occurs between two glacial stages, indicating a phase of warmer climate between colder periods.
Think of a time that occurs 'between' ('inter-') two phases or stages ('stadium') — that's what interstadial means.