To make bold.
- The Clarendon dictionary. By William Hand Browne, Samuel Stehman Haldeman. Published 1894. (verb) (v. t.) (verb transitive)
To give boldness or courage to; to encourage.
- Newage Dictionary DB (verb) (v. t.) (verb transitive)
To give boldness or courage to.
- Etymological and pronouncing dictionary of the English language. By Stormonth, James, Phelp, P. H. Published 1874. (verb) (v.) (verb)
To make brave; to encourage.
- The Winston Simplified Dictionary. By William Dodge Lewis, Edgar Arthur Singer. Published 1919. (verb) (v. t.) (verb transitive)
To make bold or courageous.
- The american dictionary of the english language. By Daniel Lyons. Published 1899. (verb) (v. t.) (verb transitive)

Usage examples:

Put case they do retain you there, as a fit property, to hire coaches some pair of months, or so; or to read them asleep in afternoons upon some pretty pamphlet, to breathe you; why, it shall in time embolden you to some farther achievement: in the interim, you may fashion yourself to be careless and impudent.
- Cynthia's Revels by Ben Jonson
I must embolden myself to speak a last warning to thee.
- The Three Heron's Feathers by Hermann Sudermann
" But your cousin does not know it," said she; " I never told him- he was not kind enough to embolden me; therefore do not blame him for my sin; he did not know of my wicked designs- he did not encourage me-" " But he forsook you, Agnes."
- Nature and Art by Mrs. Inchbald