unobserving

Mary Johnson must be unobserving in the extreme if she failed to know him, once she glimpsed him in the crowd.

This conduct, which seems odd to unobserving persons, is really very natural.

Why, I took you for an unobserving blockhead, or I would never have trusted you so near me.

I fancy it was in one of your most decided unobserving fits that you took me for a blockhead.

Unobserving gunners conclude that he has gone to the bottom of the lake, and call him the hell-diver.