As you may know, most Arabic words contain a series of three consonants in a particular order (the "triliteral root") that signifies a more-or-less specific meaning. Various patterns of vowels are inserted around & between the root elements, and prefixes and suffixes added, to modify the meaning and create the individual words. So, for example, K-T-B has to do with "writing": KaTaBa al-KaaTiB KiTaaBan fi-maKTaB-u. "The writer wrote a book in his office."
Verbs also have a number of patterns for expressing distinctions in meaning like passive, reflexive, causative, etc. One of these, Form X, creates a verbal noun by prefixing isti- to the root with the first two literals clumped together and adding an aa before the last literal; so keeping with the examples above we get istiKTaaB "dictation" (=asking, requesting, or causing someone/thing to write). That initial i- is mainly there because Arabic words can't begin with two consonants, and it disappears when preceded by a word ending in a vowel; Frank Herbert didn't indicate vowel length in his Fremen Arabic, so we would end up with stiKTaB. See where I was headed?
Unfortunately, I have not yet been able to find an Arabic root consisting of L-G-R.
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