1. Give extra weight to (a communication)
   - underline, emphasize, emphasise [Brit] 
2. Draw a line or lines underneath to call attention to
   - underline

1. A line drawn underneath (especially under written matter)
   - underline

Derived forms: underscores, underscored, underscoring

Type of: accent, accentuate, emphasise [Brit], emphasize, mark, punctuate, stress, stroke

Encyclopedia: Underscore

• throbbing
• throe
• throes
• thrombasthenia
• thrombectomy
• thrombin
• thrombocyte
• thrombocytopenia
• thrombocytopenic purpura
• thrombocytosis
• thromboembolism
• thrombokinase
• thrombolysis
• thrombolytic
• thrombolytic agent
• thrombolytic therapy
• thrombopenia
• thrombophlebitis
• thromboplastin
• thrombose
• thrombosed
• thrombosis
• thrombus
• Saxony
• Saxony blue