1. (chemistry) the theory that all indicators are either weak acids or weak bases in which the colour of the ionized form is different from the colour before dissociation
   - theory of indicators

Type of: scientific theory

• Third Baron Rayleigh
• third base
• third baseman
• third battle of Ypres
• third class
• Third Council of Constantinople
• third cranial nerve
• Third Crusade
• third deck
• third degree
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• Third Epistel of John
• third estate
• third eye
• third eyelid
• third gear
• third house
• Third Lateran Council
• third law of motion
• third law of thermodynamics
• third man
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• third rail