perioodi
Perioodi is the genitive singular form of the Estonian noun periood, which denotes a span of time, an era, or a repeating cycle. The form perioodi is used to express “of the period” or the period’s in phrases such as “ajaloo perioodi lõpp” (the end of the historical period) or “Renessansi perioodi” (the Renaissance period). In scientific and mathematical contexts it can describe the duration of one cycle, for example “signaali periood” (the period of a signal) or “perioodi pikkus” (the length of the period), as well as “perioodi jooksul” (during the period).
Perioodi is derived from periood, a word borrowed from the wider European term for a time span,