What is "major second"

Major \Ma"jor\, [L. major, compar. of magnus great: cf. F. majeur. Cf. Master, Mayor, Magnitude, More, a.]

1. Greater in number, quantity, or extent; as, the major part of the assembly; the major part of the revenue; the major part of the territory.

2. Of greater dignity; more important.
   --Shak.

3. Of full legal age; adult. [Obs.]

4. (Mus.) Greater by a semitone, either in interval or in difference of pitch from another tone.

   Major key (Mus.), a key in which one and two, two and three, four and five, five and six and seven, make major seconds, and three and four, and seven and eight, make minor seconds.

   Major offense (Law), an offense of a greater degree which contains a lesser offense, as murder and robbery include assault.

   Major scale (Mus.), the natural diatonic scale, which has semitones between the third and fourth, and seventh and fourth, and seventh and eighth degrees; the scale of the major mode, of which the third is major. See Scale, and Diatonic.

   Major second (Mus.), a second between whose tones is a difference in pitch of a step.

   Major sixth (Mus.), a sixth of four steps and a half step. In major keys the third and sixth from the key tone are major. Major keys and intervals, as distinguished from minors, are more cheerful.

   Major third (Mus.), a third of two steps.

n. (context music English) an interval that is equivalent to two half steps

In Western music theory, a major second (sometimes also called whole tone) is a second spanning two semitones . A second is a musical interval encompassing two adjacent staff positions (see Interval number for more details). For example, the interval from C to D is a major second, as the note D lies two semitones above C, and the two notes are notated on adjacent staff positions. Diminished, minor and augmented seconds are notated on adjacent staff positions as well, but consist of a different number of semitones (zero, one, and three).

The major second is the interval that occurs between the first and second degrees of a major scale, the tonic and the supertonic. On a musical keyboard, a major second is the interval between two keys separated by one key, counting white and black keys alike. On a guitar string, it is the interval separated by two frets. In moveable-do solfège, it is the interval between do and re. It is considered a melodic step, as opposed to larger intervals called skips.

Intervals composed of two semitones, such as the major second and the diminished third, are also called tones, whole tones, or whole steps
One source says step is "chiefly US."
The preferred usage has been argued since the 19th century:

• "Mr. M. in teaching the Diatonic scale calls a tone a step, and a semitone a half step; now, who ever heard of a step in music, or in sound ? Can any one suppose that a pupil will understand the meaning of tone and semitone any sooner by calling them step or half step, … ?"
• "… to use the term tone for a whole step is certainly objectionable …"

In just intonation, major seconds can occur in at least two different frequency ratios: 9:8 (about 203.9 cents) and 10:9 (about 182.4 cents). The largest (9:8) ones are called major tones or greater tones, the smallest (10:9) are called minor tones or lesser tones. Their size differs by exactly one syntonic comma (81:80, or about 21.5 cents). Some equal temperaments, such as 15-ET and 22-ET, also distinguish between a greater and a lesser tone.

The major second was historically considered one of the most dissonant intervals of the diatonic scale, although much 20th-century music saw it reimagined as a consonance. It is common in many different musical systems, including Arabic music, Turkish music and music of the Balkans, among others. It occurs in both diatonic and pentatonic scales.

. Here, middle C is followed by D, which is a tone 200 cents sharper than C, and then by both tones together.