1. The boundary between Maryland and Pennsylvania; symbolic dividing line between North and South before the American Civil War
   - Mason-Dixon line, Mason and Dixon's line

Type of: state boundary, state line

• Trionychidae
• Trionyx
• Trionyx muticus
• Trionyx spiniferus
• Triopidae
• Triops
• triose
• Triostium
• Triostium perfoliatum
• trioxide
• trip
• trip hop
• trip line
• trip out
• trip the light fantastic
• trip the light fantastic toe
• trip wire
• trip-up
• tripalmitin
• tripartite
• tripe
• triphammer
• triphosphopyridine
• triphosphopyridine nucleotide
• triphosphoric acid