Open English Wordnet
Verbs
(v)strengthen, beef up, fortifymake strong or stronger“This exercise will strengthen your upper body”,
“strengthen the relations between the two countries” (v)arm, build up, fortify, girdprepare oneself for a military confrontation“The U.S. is girding for a conflict in the Middle East”,
“troops are building up on the Iraqi border” (v)fortifyadd nutrients to“fortified milk”