Most of them are combining forms in Neo-Latin and hence international scientific vocabulary. There are a few general rules about how they combine. First, prefixes and suffixes, most of which are derived from ancient Greek or classical Latin, have a droppable vowel, usually -o-.
The majority of these terms are created through Neo-Latin combinations and function as an international vocabulary in science. Certain fundamental rules dictate their combination. Initially, prefixes and suffixes, mostly originating from ancient Greek or classical Latin, usually shed the vowel -o-.