Omniconsonant scale
Omniconsonant scale is a type of note arrangement where all notes pairwise make consonant intervals, and by extension consonant chords of any size.
To put it simply: if a person were to smash the keyboard tuned to such a scale, no matter what would come out, it would be a consonance.
Theory
Omniconsonant scales have to be defined in the relation to what a particular system defines as “consonance”.
Examples
For example, in the standard 5-limit theory of Western music and it's diatonic and Pythagorean backing, 12edo is not an omniconsonant temperament - P4 and P5 are consonances, thirds, sixths less so, and seconds and sevenths are dissonant, with the lowest consonance being semitone and tritone. However, if taken in 2.3.7.17.19 subgroup, tritone gets to be 7/15 or 10/7, a semitone 17/16, two thirds being 19/15 and 19/16, making all 12 notes pairwise consonant.
It is therefore possible to say that any EDO is omniconsonant in regards to a particular JI choice, since every irrational number has infinitely many close rational numbers around it.
It's possible to argue that just intonation is omniconsonant by definition - as all the intervals form the basis of what is considered "harmonious", harmony by definition coming from ratios of integers, they define also what consonance means and thus are themselves all by definition consonant. However, JI practitioners such as Kyle Gann would argue that dissonance does exist in JI, which is once again a relative statement. A comma-step interval is dissonant relative to the interval which it differs from such as 40/27 against 3/2, however if one were to be as elaborate as to make a system involving thousands of pitches and commas as individual steps, then an interval like 40/27 can assume the role of the consonance.
5edo
5edo may be the only temperament which is omniconsonant from the Western music theory perspective - 3\5 makes a perfect fifth, 1\5 makes a vaguely supermajor second of 8/7, 4\5 makes a vague seventh, and due to small amount of notes rotations of these intervals are too consonant. 5edo itself is vaguely the slendric pentad, which finds use in Indonesian music.
7edo
7edo tempers all its intervals to neutral, them being simply second, third, fourth, etc. As such, with multiple interpretations tempering to one, it's possible to play a 7edo scale as if all its notes have the same harmonic value.