An Etymological Dictionary of Astronomy and Astrophysics
English-French-Persian

1) Paying strict attention.
2) Careful in observing (Merriam-Webster.com).

→ observe + -ant, a suffix forming adjective, → -ance.

Nepâhdâr, from nepâh present stem of nepâhidan, → observe, + dâr preset stem and agent noun of dâštan, dâridan "to have, hold, maintain, possess," → protected band.