Stemmatology is the global term denoting all scholarly and scientific studies involving a text's genealogy and stemma codicum. It is usually concerned with reconstructing such a stemma, but may also study stemmata in a more abstract sense (hence this lexicon's name). The term is usually used synonymously to stemmatics. As with many other fields the endings -ology (from λόγος 'word, meaningful or scientific utterance') and -ic(s) (the adjective forming suffix -ικὴ with an intended feminine τέχνη 'art, field of study') tend to be used for the same purpose, namely to label a 'science of X'.
If a difference between the two terms is perceived, stemmatology tends to be the wider term, whereas stemmatics may be confined to the Lachmannian method.
The Latin term 'stemmatologia' was already in use in the 17th century in the work Stemmatologia Sangallensis oder Geschlecht-Register aller in der Stadt St.Gallen verbürgerten und sich noch im Wesen findenden Geschlechtern, [...] bis auf das Jahr 1732 von Johann Jacob Scherrer [...]. St. Gallen 1752-1769, 27 volumes. But here the stemmata it studies were people's genealogical trees and not yet those of manuscripts. The word stemmatographia was used synonymously (cf. J. Ramminger, stemmatographia, in ders., Neulateinische Wortliste. Ein Wörterbuch des Lateinischen von Petrarca bis 1700, URL: www.neulatein.de/words/1/001317.htm (used on 12.12.2014)).