Tenorlied: A German song, in which the tenor vocal line predominates, or has the melody.
Third: The interval of three diatonic degrees.
Tie: A curved line drawn over or under the heads of two notes of the same pitch indicating they should be played as a single note.
Time Signature: The numbers written on staff of any piece, indicating which type of note gets a single beat, and also how many beats are in each measure.
To the Color: A bugle call honoring the US that's used when the national anthem cannot be played (such as when no band is available), or when the national anthem has been played already but honor is to be rendered again.
Tombeau: A musical composition commemorating the death of a perosn, usually someone notable.
Tonal: Music with a center, or tonic, which employs tones which relate to that tonic in a predictable and measurable manner.
Tonic: The key center, or foundation of, a scale or melody.
Treble: The highest voice, instrument, or part.
Trill: An ornament consisting of a rapid alternation between two pitches, the main pitch, and the pitch a whole or half step above it.
Turn: An ornament consisting of four or five notes that move up and down 'around' a given pitch, using that pitch as a tonal center.
Twelve-Tone Music: Music in which no pitch class (or note) is repeated until all other chromatic pitches have been used. Any group of twelve pitches arranged this way is called a row.