Words are borrowed into Lojban as fu'ivla.
In day-to-day use, such borrowing can be and in fact already are ad hoc, without much damage being done — mainly because all Lojbanists currently share English as a source of loans. For consistency and respectability, however, it is desirable to have canonical loan word forms, both in transliteration and in morphology, for inclusion in a Lojban dictionary.