FromOld Englishforebiseġian,forebisġian, equivalent tofore- +busy.
forebusy (third-person singular simple presentforbusies,present participleforebusying,simple past and past participleforebusied)
- (rare, nonstandard, transitive) Tobusy beforehand;preoccupy.
1877, Philip James Bailey,Festus:Springs up to know all life, the secrets learn / Of science and time's truths arcane; projects / Evil would fulfil, that thusforebusied, soul, / All virtue of self-ascription to its Lord Might lose.
2011, David Cowley,How We'd Talk If The English Had Won in 1066:Or who might beforebusied, and onbeloaded with work?