fortify

for|ti|fy /f'ɔː^rtɪfaɪ/ (fortifies fortifying fortified)
1 [VERB] V n
To fortify a place means to make it stronger and more difficult to attack, often by building a wall or ditch round it.
...British soldiers working to fortify an airbase in Bahrain.
2 [VERB] usu passive, be V-ed with n, V-ed
If food or drink is fortified, another substance is added to it to make it healthier or stronger.
It has also been fortified with vitamin C...
...fortified cereal products.