When I of speak of direction, I'm speaking about our perception relative to the earth. We all intuitively know about all three directions. For instance, if we throw a ball, it is moving constantly forward, and simultaneously moves up and then down, but never left or right. What I need however, is a technical term for all three directions.

To add some context, I are studying the auditory system, and I need a shorthand term for each direction. Unfortunately, it seems that length/width are used interchangeably, with only height being used consistently. I want to work with the terms horizontal/vertical, but there's no term I can find to describe the z axis. Furthermore, from what I've read, many people define the horizontal direction as being the horizontal and vertical direction, with height being described as the vertical direction i.e, horizontal = area, vertical = height.

The thing is though is that everyone knows what left and right, backwards and forwards, and up and down are, everyone, and this I believe is because these directions relate to our own perception (rather than an objects).

So right now as far as my nomenclature, it's a huge mess. It would be so nice if there is a single word that describes each of these three directions without ambiguity.

  • 1
    Possible duplicate of X, Y, Z — horizontal, vertical and ...?
    – choster
    Commented Apr 12, 2016 at 22:56
  • Was "I are" a typo?
    – Spencer
    Commented Apr 13, 2016 at 1:19
  • I'm guessing that what you want to do is to locate the source of a sound relative to the hearer. Is that correct? If so then your directions should probably be relative to which way the person is facing. Different disciplines use different terminology: aircraft pilots, sailors and anatomists each have their own way of describing this and they don't all use (x,y,z) coordinates. Some use angular measures and speaking personally as a boater, angles are easier to work with. I've never met a novice canoeist who didn't understand "The dock is at five o'clock, a hundred meters away."
    – Al Maki
    Commented Apr 13, 2016 at 2:04

3 Answers 3


Consider using Transversal or Sagittal. As you pointed out it is hard to describe such a concept because the position you want to describe is extra-relatal from the observer unlike common directional words we use. North and South are close but they are not usually imagined from the first person point of view are are un-conviently pointed to a fixed spot on the horizon in this case. Since you mentioned a third term to coalesce with horizontal and vertical the answer will be a bit subjective because the way the distances and movement between points can be described are similar in both the sagittal and transverse planes. What you are describing is comparing two points along the intersection of the horizontal and vertical planes or more likely between the sagittal and transverse planes.


In this case consider using Transversal. The intersection of the vertical plane with the horizontal plane would form a transverse. This medical definition from thefreedictionary.com describes:

transverse plane of space, n an imaginary plane that cuts the body in two, separating the superior half from the inferior half, and that lies at a right angle from the body's vertical axis.

And the definition for sagital:

sagittal plane


A longitudinal plane that divides the body of a bilaterally symmetrical animal into right and left sections.

Since forward and backward movement at the intersection of the vertical planes is what you are describing, transverse or transversal may be a better choice, however when we describe vertical it is ambiguous whether we are describing a sagittal plane or a coronal

Because of this it is still necessary to describe the relative position between the points. You can use biological or aeronautical terms to describe forward and backward through the transverse plane: dorsal/posterior or aft for back and ventral/anterior and fore for forward.


After reading some of the other answers it seems clear to me that you are stuck with either a frame of reference to the earth or from the point of view of self. Perhaps the answer here is to abandon the term vertical and horizontal and use for coronal, sagittal, and transversal although that still does not solve your earth point of view in which case you can use latitude, longitude, and altitude.

But keep in mind it's all relative. Pick a system and stay consistent.

  • 1
    Thank you very much for your answer. From what you've wrote, but more importantly from what you've shown, I can see that describing the relationship between the three axis (lxy, xz, and yz) may also be problematic. I didn't mention such an issue, but that's because I overlooked that, and I imagine as my studies become more in depth I will have to look at such relationships :) Commented Apr 14, 2016 at 17:28
  • As you look at this you'll also discover that there's little standard for 'handedness' either. When working with accelerometers and gyroscopes, one must know their handedness, in order to manage the polarity of the axes. While 3D math almost always assumes that the positive axes go left, up, and forward, lots of devices and specialized knowledge don't conform. This is an interesting read: en.wikipedia.org/wiki/Right-hand_rule
    – Taryn
    Commented Jun 8, 2019 at 1:26

In airplanes, it is yaw, pitch and roll describing motion around each axis. Not a pilot myself, but I believe it is positive/negative degrees from the neutral standard.

From Wikepedia: An aircraft in flight is free to rotate in three dimensions: pitch, nose up or down about an axis running from wing to wing; yaw, nose left or right about an axis running up and down; and roll, rotation about an axis running from nose to tail. Aircraft principal axes - Wikipedia

  • The same is used on the ocean, I believe.
    – Jelila
    Commented Feb 1, 2018 at 11:03

There are standards for this, precisely because it is a basically arbitrary decision, and it's very hard to compare published works if everyone uses their own system. You want the body fixed coordinate system for the ear's perspective of the world, and the NED earth coordinate system for the fixed reference frame. Be glad you aren't trying to land a probe on an asteroid via multiple slingshot maneuvers. Those poor sods have dozens of coordinate systems to keep track of. Body doesn't mean human body, it means anything like an airplane free to move about.


  • 2
    "The enemy's gate is down."
    – TK-421
    Commented Apr 13, 2016 at 1:06

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