Dictionary of Medieval Names
from European Sources

Bonaparte m. Latin bona 'good, kind, right, pleasant; valid, useful, healthy' + Latin pars 'part, share'.

The 11th C example of Bonus Pars indicates a scribe who doesn't know his Latin very well; pars is a feminine name and so should not be modified by masculine bonus.

France
Latin
1065x1079 Bonus Pars (nom) StVdM-II 663; 1069 Bombpars (nom) ibid. 717
Italy
Latin
1285 Bonaparte (gen) Perugia1285 p. 154
Cite as: S.L. Uckelman. "Bonaparte". In S.L. Uckelman, ed. The Dictionary of Medieval Names from European Sources, Edition 2016, no. 4. http://dmnes.org/2016/4/name/Bonaparte.