de ri·gueur 
(də rē-gœr)
(də rē-gœr)adj.
Required by the current fashion or custom; socially obligatory.
[French : de, of + rigueur, rigor, strictness.]
- astringently
- astrionics
- astro-
- astrobiological
- astrobiologist
- astrobiology
- astrobleme
- astrochemist
- astrochemistry
- astrocyte
- astrocytic
- astrocytoma
- astrodome
- astrogate
- astrogation
- astrogator
- astrogeological
- astrogeology
- astrolabe
- astrologer
- astrologic
- astrological
- astrologically
- astrology
- astrometric