Use 'anachronistic' when discussing history or tradition to highlight something that doesn't fit the era. The knight's fiberglass shield felt anachronistic in the medieval reenactment.
Pro Tip 2/3
Cultural Reference
Understand specific eras to identify anachronistic elements that may not match that time period. The movie about ancient Rome had anachronistic dialogue, with characters saying 'okay.'
Pro Tip 3/3
Intentional Use
Sometimes 'anachronistic' is used purposely in stories to create humor or contrast. The time-travel film humorously featured an anachronistic pop song in a Victorian ballroom.