Is there a formal name for tones occurring at the same instant?

Question

I am not talking about chords. Imagine a score with two staffs (e.g. for piano) and let's say 2 voices. In the first measure on the upper staff we have some chord (let's say it consists of 4 notes) and all the notes of this chord are crochets. Then, on to bottom staff, in the second voice, we have two eighths. So the crochet-chord and first eighth form kind of "acoustic block" that produce to sound together. Then, after eighth interval there we have second "block" with the second eight of second voice. So we have there two "blocks" of sound. Does this block have some formal name, then?

Update: The answer is simultaneity.

According to Wikipedia:

In music theory, a pitch simultaneity is more than one pitch or pitch class all of which occur at the same time, or simultaneously: "A set of notes sounded together."[1]

Simultaneity is a more specific and more general term than chord: many but not all chords or harmonies are simultaneities, though not all but some simultaneities are chords. For example, arpeggios are chords whose tones are not simultaneous. "The practice of harmony typically involves both simultaneity...and linearity."[2]

So I am accepting @Richard answer as it is precise answer to may question. Thank you!

Answer 1

A common term in the study of twentieth-century music is simultaneity, which simply means "a collection of musical entities that sound simultaneously."

It's odd, because that's really all that "harmony" means. But I think "harmony" often has some (incorrect) baggage that suggests it must be harmonious/consonant, which isn't always true.

In less formal discourse, I've heard "blocks" or "sound blocks" plenty, so you should feel free to use those terms, as well. As long as it gets the point across—which these all do—you should be in good shape.