Anachronism (noun)

Something that is out of place in terms of historical or chronological context, such as a person or object that belongs to a different time period than the one in which it is located.

Origin:

From greek ἀνά (ana-, "back") + χρόνος (chronos, "tim.e")

Examples:

1. The portrayal of cell phones in a historical movie set in the 1800s is an anachronism.
2. The use of the word "awesome" in a historical novel set in the 1700s is an anachronism.
3. The painting depicts a knight in armor, but the armor is an anachronism, as it was not in use at the time the painting is set.
4. The anachronism was pointed out by the historian who noticed the mistake.
5. The anachronism stood out like a sore thumb in the otherwise historically accurate reenactment.