Atypical and Off-base

Atypical adjective - Being out of the ordinary.

Off-base and atypical are semantically related In some cases you can use "Off-base" instead an adjective "Atypical".

Off-base adjective - Located outside a military base.

Atypical and off-base are semantically related in different from standard or norm topic. Sometimes you can use "Atypical" instead an adjective phrase "Off-base", if it concerns topics such as not normal.