About 5 d. ago I turned on dynamic spelling for the first time in iD. I have tried rather conscientiously to fill my Mac user dictionary with terms that I use a lot. Wondering if there is a way to point inDesign to that dictionary first, before turning strange words red. Two days ago I "merged" my user dictionary into inDesign. I work a lot with orchids. Genus names like Phalaenopsis "passed" here while writing this, along with many others, but is red in inDesign. Would appreciate any insight on this issue.
The Mac user dictionary is not compatible to InDesign as InDesign has to be compatible with all Windows and Mac systems. You will have to build up an InDesign user dictionary, you can import lists in the spell checking dialog to build up a user dictionary.
Use the language you need, write some words from InDesign to your user dictionary, export this as text file, open this file to see how the syntax is and complete this list and import them into your program. In many cases you could find such dictionaries in the web to buy and to import.