Tonic may refer to:

• Tonic water, a drink traditionally containing quinine
• Soft drink, a carbonated beverage
• Tonic (physiology), the response of a muscle fiber or nerve ending typified by slow, continuous action
• Tonic syllable, the stressed syllable of a word
• Herbal tonic, a herbal medicine with tonic effects
• Tonic (music), the tonal center of a musical scale
• Tonic (band), an American rock band
• Tonic (Tonic album), 2010
• Tonic (music venue), a New York City music venue, 1998–2007
• Tonic (Medeski Martin & Wood album), 2000
• Tonic (radio program), Canadian radio program
• Tonic suit, a garment made from a shiny mohair blend that was fashionable among the Mods of the mid 1960s
• Tonic (film), a Bengali film

• All pages with titles beginning with Tonic
• All pages with titles containing Tonic
• Patent medicine that claims to have tonic properties
• Tonči
• Tonic sol-fa, a method of teaching sight-singing
• Tonic Sol-fa (a cappella group), American singing group with a largely pop-music-oriented repertoire
• Tonie, name
• Tonio (name)