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
   - Ostwald's theory of indicators

Type of: scientific theory

• ultra-high
• Ultracef
• ultracentrifugation
• ultracentrifuge
• ultraconservative
• ultrahigh frequency
• ultraism
• ultramarine
• ultramarine blue
• ultramicroscope
• ultramicroscopic
• ultramodern
• ultramontane
• ultramontanism
• ultramundane
• ultranationalism
• ultranationalistic
• ultrasonic
• ultrasonically
• ultrasonics
• ultrasonography
• ultrasound
• Ultrasuede
• ultraviolet
• ultraviolet illumination