From BiblePortal Wikipedia

King James Dictionary [1]

Doubtless, a. Free from fear of danger secure.

Pretty child, sleep doubtless and secure.

Doubtless, adv. Without doubt or question unquestionably.

The histories of Christ by the evangelists are doubtless authentic.

Webster's Dictionary [2]

(1): ( adv.) Undoubtedly; without doubt.

(2): ( a.) Free from fear or suspicion.