Backup and Fallback

Backup noun - A crowded mass (as of cars) that impedes or blocks movement.

Fallback and backup are semantically related in switch topic. In some cases you can use "Fallback" instead the word "Backup" as an adjective or a noun.

Nearby Word: backing

Fallback noun - To break off a military action with an enemy.

Backup and fallback are semantically related in switch topic. You can use "Backup" instead the word "Fallback" as a noun or an adjective, if it concerns topics such as replacement.