Diatonic the seven note scale with its octave. The steps of a diatonic scale are not all the same size. The distance between B and C, and between E and F, is half the size of the other steps.
Pentatonic can apply to a tune founded on any five notes
Dominant the fifth degree of any scale. The to and fro between tonic and dominant can be felt when singing a phrase such as the begining of 'God rest you merry, Gentleman'.
Dorian the tonic is D. The semitones are between the second and third and the sixth and seventh degrees.
Ionian the tonic is one. The semitones are between the third and fourth and the seventh and eighth degrees.
Lydian the tonic is four. The semitones are between the fourth and fifth and the seventh and eighth degrees.
Mixolydian the tonic is five. The semitones are between the third and fourth and the sixth and seventh degrees.
Phrygian the tonic is E. The semitones are between the first and second and fifth and sixth degrees.
