Wikipedia
A cultureme is any portion of cultural behavior apprehended in signs of symbolic value that can be broken down into smaller units or amalgamated into larger ones.
Their usage can be seen in cultural expressions, phraseologisms, jokes, slogans, literature, religion, folklore, sociology, anthropology, etc.
The notion of cultureme is being increasingly used in translation studies and other disciplines. It is a recently used concept that is yet to be defined and distinguished from others, such as phraseme, idiom, symbol, cultural word, etc.
Translating a cultureme can be challenging, as connotations are sometimes very strong. For instance: the Spanish word alcázar means "the castle", "palace" or "fortress", but, as it is of Arabic origin, it recalls eight centuries of history ( Al Andalus), which cannot be easily translated into English, so the translator must adopt a crucial decision: either choose the English word "fortress" and lose all the historical and cultural connotations, or use the loan word alcazar.