Do is the first syllable in Solresol's alphabet. It can be represented with the written or spoken 'do', the letter 'd', the color red, a circle (in the Solresol stenography), the number 1, the musical note C (in fixed do solfège), or the base note of any major musical scale (in movable do solfège). It is followed by the note re.

The word do means "No, not, neither, nor." It is generally used as a negative, or negating word. It precedes the word that it negates. For example, the sentence Dore do milasi domi translates as "I do not love you".

Four-syllable words beginning with the syllable do are generally related to "physical and moral man, his intellectual faculties and his qualities, and to food."

The word dodo, sometimes written as DO, indicates that a verb is in the preterite or imperfect tense.

Words beginning with do that are either four syllables with a repeated syllable in them or three syllables are generally dedicated to religion.