fortify

transitive verb fortified, fortifying

1. to make strong or stronger; strengthen physically, emotionally, etc.
2. to strengthen against attack, as by building or furnishing with forts, walls, etc.
3. to support; corroborate: to fortify an argument with statistics
4. to strengthen (wine, etc.) by adding alcohol
5. to add vitamins, minerals, etc. to (milk, etc.) so as to increase the food value; enrich

intransitive verb