Sesquialtera ('one and a half') may refer to:

• Sesquialterum in mathematics, the ratio 3:2, a superparticular ratio
• Sesquialtera or the equivalent Greek term hemiola, three in the time of two as variously used in music theory:
  • Sesquialtera commonly describes a tempo proportion in mensural notation
  • Hemiola is more common for the temporary substitution of a 2+2+2 musical meter for 3+3
• Sesquialtera (organ stop), combining mutation ranks at 22⁄3' and 13⁄5', i.e. both 3:2 and 5:4 pitch ratios
• Sesquialtera (moth), a genus of moth in the family Geometridae

This disambiguation page lists articles associated with the title Sesquialtera.
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