The Persian lexicon has a very large number of Arabic borrowings, including a small portion of very frequently used ones, and a larger portion of Arabic vocables seemingly spanning across all semantic domains. Much of the “Arabic” vocabulary used in the languages of the Indian subcontinent has been introduced indirectly through Persian.
I am wondering if there are any known patterns—phonetic, semantic, or otherwise in Arabic words Persians were exposed to but never adopted in their own language. To give an example for comparison, the sound ژ is somewhat common in Persian but practically all words including it were not borrowed into the Indic languages.
Besides function words and morphemes like the definite ال what tendencies in Arabic vocabulary would still stand out as entirely foreign against words current in Persian?