opiskellessani
Opiskellessani is a Finnish word that translates to "while I was studying" or "during my studies." It is the past tense of the present participle of the verb "opiskella," which means "to study." The word is used to describe an action or event that occurred during the period of a person's education.
For example, one might say "Tapasin hänet opiskellessani yliopistossa," meaning "I met him while I was studying