1. A very thin line 
2. The natural margin formed by hair on the head

Derived forms: hairlines

Type of: bound, boundary, bounds, line

Part of: hair

Encyclopedia: Hairline

• third trimester
• third ventricle
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• third-degree burn
• third-dimensional
• third-dimensionality
• third-place finish
• third-rate
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• thirst
• thirst for knowledge
• thirster
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• thirteen
• thirteenth
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• thirtieth
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• Thirty Years' War