/ ʌnˈgɑːdɪd; NAmE -ˈgɑːrd-/ adjective
1.
not protected or watched :
The museum was unguarded at night.
an unguarded fire (= that has nothing to stop people from burning themselves on it)
2.
( of a remark, look, etc. ) said or done carelessly, at a time when you are not thinking about the effects of your words or are not paying attention :
an unguarded remark
It was something I'd let out in an unguarded moment .
—compare guarded