Term Htra may refer to:

• High time-resolution astrophysics, a section of astronomy/astrophysics
• Peptidase Do, an enzyme

• Solidarite francaise
• SolidariteS
• Solidarite Scolaire (Baie-Mahault)
• Solidaritetsfronten foer Indokinas Folk
• Solidaritetsfronten for Indokinas Folk
• Solidarity and Equality
• Solidarity Bridge
• Solidarity (Catholic Theology)
• Solidarity Contribution (football)
• Solidarity Day march
• Solidarity (disambiguation)
• Solidarity Front for Development of the Cambodian Motherland
• Solidarity - Kosovo is Serbia
• Solidarity movement
• Solidarity Movement
• Solidarity Party (Lebanon)
• Solidarity (social science)
• Solidarity (social sciences)
• Solidarity (South Africa)
• Solidarity (South African trade union)
• Solidarity Sweden-Latin America
• Solidarity - The Union for British Workers
• Solidarity (trade union)
• Solidarity - Work - Peace - Ecology
• Solidarity youth movement