fortify

To give power, strength, or vigour to (oneself or someone, or to something); to strengthen.

[I]t [“oleum de costo”] fortifyeth yͤ ſtomack and Lyuer, it keepeth the hayre from fallyng of, & the head from horeneſſe [hoaryness], it cauſeth good colour, and ſauour in all the body.

[…] I preſum'd it vvill not be unvvelcome to Your Lordſhip, if I here fortifie the Speculations that have been or may be propos'd to explicate theſe things according to the Hypotheſis of the vveight of the Air, by vvhat vve tried to that purpoſe, among others, vvhen vve vvere making uſe of a Syringe in our Engine.

To support (one's or someone's opinion, statement, etc.) by producing evidence, etc.; to confirm, to corroborate.

And vnto that texte he wold haue made you a gloſe, that his father and he were one not in ſubſtaunce but in will. And that gloſe he would haue fortified and made ſomewhat ſemely with an other worde of Chriſt, […]

[I]t may ſerue for no ſmal iuſtification of the tranſlatour that he fortifyeth his tranſlation vvith the authority of ſuch an auncient manuſcript, vvritten aboue eleuen hundred yeares ago, […]

To increase the nutritional value of (food) by adding ingredients, especially minerals or vitamins.

Soy milk is often fortified with calcium.

Compare the nutrition information label of a regular ready-to-eat fortified cereal with that of a presweetened brand and you'll note that, although the sweetened one's sugar content is higher, the fortification is virtually identical.

To impart fortitude or moral strength to (someone or their determination, or something); to encourage.

[H]er ovvne proofe taught her to knovv her mothers minde; vvhich […] greatly fortified her deſires, to ſee, that her mother had the like deſires. And the more iealous her mother was, the more ſhe thought the Ievvell precious, vvhich vvas vvith ſo many lookes garded.

[…] I had rather vvrite of you to others, to provoke them to imitate ſo excellent an Example, than to your Self, to encourage you in your Chriſtian Courſe, and to fortifie you in your Athletick Conflicts vvith the greateſt of temporal Evils, bodily Pain and Anguiſh; […]

To make (something) defensible against attack by hostile forces.

For if they fell upon one kind of ſtrictneſſe, unleſſe their cure vvere equall to regulat all other things of like aptnes to corrupt the mind, that ſingle endeavour they knevv vvould be but a fond labour; to ſhut and fortifie one gate againſt corruption, and be neceſſitated to leave others round about vvide open.

It is, ſay the American advocates, the natural diſtinction of a freeman, and the legal privilege of an Engliſhman, that he is able to call his poſſeſſions his ovvn, that he can ſit ſecure in the enjoyment of inheritance or acquiſition, that his houſe is fortified by the lavv, and that nothing can be taken from him but by his ovvn conſent.