plural of border
"The two countries share several long borders that stretch across mountains and rivers."
Third-person singular simple present indicative form of border
"The river borders the city on three sides."
In plain English: To border something means to touch it along its edge without going all the way across.
"The storm borders on being unbearable tonight."
plural of Border
"The border between the two provinces is marked by a river that has changed course over centuries."