Some music is written with 'block' chords, some has weaving parts around the tune, and some music has no harmony at all. These are all examples of textures in music.
Chordal accompaniment is where different instruments or parts play or sing the same notes. Music that has no chordal accompaniment is described as in unisonWhen all voices or instruments sing or play the same melody at their chosen octave..
Monophonic
Monophonic means there is only one line of music - one instrument or singer. There is no accompaniment or secondary melody. The term monophonic can be used for single lines - this could be solo, unison or octave doubling.
Gregorian chant is monophonic - all the monks sing the same melody together.