der is a form of:

Era



noun — Plural: Eras
1.
(a period of history, a date that marks the beginning of a new period in the history of something, a fixed point of time from which a series of years is reckoned, epoch, time, age, a memorable date or period) ស័ក, សករាជ, យុគ, សម័យ, ជំនាន់, រដូវ, អាយុកាល, វ័យ
Example: We are living In the computer era.
2.
(បច្ចេកទេស) យុគសម័យ
  • interglacial era
    - អន្តរប្រវត្តិកាលទឹកកក
ENGLISH MEANING
noun — Plural: Eras
1.
A fixed point of time, usually an epoch, from which a series of years is reckoned.
2.
A period of time reckoned from some particular date or epoch; a succession of years dating from some important event; as, the era of Alexander; the era of Christ, or the Christian era.
3.
A period of time in which a new order of things prevails; a signal stage of history; an epoch.
1.
age, antiquity, date, epoch, generation, period, time