1. To wander in(to some place), especially when one is not supposed to be there. Make sure not to leave the back doors open, or feral cats will stray in during the night. Some child strayed in the laboratory and began fiddling with the sensitive machinery inside.

2. To wander aimlessly around some place. A noun or pronoun can be used between "stray" and "in." Don't let the children stray in the forest, or they will surely get lost. We were just idly straying in the field, admiring the silence of the falling snow.