Green’s Dictionary of Slang

bone adv.

[SE bone; i.e. to one’s very depths]

(US black) thoroughly, completely.

[US]E. Pound letter 18 Mar. in Paige (1971) 271: I am bone ignorant of the subject, but have vague feeling that something or other, etc.
[US](con. 1969) M. Herr Dispatches 9: Even bone-dumb grunts seemed to feel that something weird and extra was happening to them.
[UK]L. Mantell Murder and Chips 129: He was bone tired.
[UK]G. Iles Turning Angel 204: He actually used the term ‘bone-dumb bluegums’ in front of me once.