To strengthen, especially by addition or augmentation.
"The engineer decided to reinforce the bridge's foundation by adding extra steel beams to ensure its stability against future floods."
In plain English: To reinforce something means to make it stronger, more effective, or better by adding support or encouragement.
"The captain reinforced the orders by repeating them to every crew member before departure."
Usage: Avoid using "reinforce" to mean "encourage," as the word specifically implies adding physical support or structural strength rather than providing moral motivation. In casual speech, speakers often confuse it with "refine," but these verbs have distinct meanings regarding strengthening versus improving quality.
The word comes from combining the prefix re- with inforce, which itself derives from Latin meaning to make strong or firm. It entered English as a compound of these elements to describe the act of strengthening something again.