Complex sentence: Much of the information in the dictionary published in 1989 was already decades out of date: though the supplements had made good progress towards incorporating new vocabulary, many definitions contained outdated scientific theories, historical information, and moral values.
Split into simpler sentences: Much of the information in the dictionary published in 1989 was already decades out of date, though the supplements had made good progress towards incorporating new vocabulary. Yet many definitions contained outdated scientific theories, historical information, and moral values.