See the Wikipedia article on "syncretism" for a more in-depth understanding of the word, which is secular and can have either a positive or negative connotation, depending on our religious beliefs.
Although lacking a citation, I found this sentence helpful in providing other possible synonyms and ways of thinking about syncretism:
"Hinduism, Buddhism and Jainism in ancient India have made many adaptations over the millennia, assimilating elements of various diverse religious traditions."
I am very grateful that my own religion, Vajrayana Buddhism of the Nyingma School, incorporated many of the local beliefs and practices when it was brought from India to Tibet in the 8th Century by Padmasambhava, also known as Guru Rinpoche, and considered by followers as "the second Buddha." Vajrayana Buddhism is highly syncretic and seeks "the truth," willing to assimilate not only indigenous religious beliefs, such as the earlier shamanistic religions of Tibet (often but mistakenly referred to as "Bon"), but also the latest discoveries of science as they become known.