transitive. Originally: to beset or harass (a person, the mind) in the manner of a besieging army or evil spirit; (now) spec. to fill the mind of…

to bite one's nails: to be nervous; to be bored; (also) to think hard, to concentrate.

to doubt of: to fear for, be in fear about.

transferred. With adverb (e.g. out, down) or adverbial phr.: To get or bring into a specified condition by harassing treatment, persistent…