It originated primarily from English and various Slavic tongues, along with numerous other ancient Earth languages. As with any language, over the millennia it evolved and adopted various cultural markers.
Galach was spoken in one form or other by the majority of conventional humans, as well as by some genetically altered human, such as futars and the Bene Tleilax. Written Galach was generally understood from one planet to another, despite regional dialects.
Several groups spoke Galach in addition to specialized languages (e.g. the Atreides Battle Language) and arcane variants (e.g. the native Fremen language). Other groups spoke Galach in addition to ancient Earth languages or older largely obsolete languages like Chakobsa. An example of this was the Bene Gesserit Sisterhood: Reverend Mothers periodically spoke old French.
- Atreidean Galach: baradit nehiidit beed gwarp tau nubukt
(A bird in the hand is worth two in the bush)
(Colonel Bashar, literally Colonel-General -- Derived from the Russian and Cold War Eastern Bloc military rank, but here expressed from the Turkish, pasha -- nobleman, general.)
Virtually all Dune works feature Galach, however the novels where it is mentioned by name are: