I'm looking for a fitting word in the context of design/engineering. We have long structural members that go in an assembly and we need to be able to describe them based on their orientation and location.

EDIT: I'm looking for a word that makes sense in the following context: Positions Image

EDIT (CONT'D): Someone putting this thing together in the real world should be able to pick up a flange labeled "[word for top-and-bottom] flange" and confidently put it in the right place.

We have an appropriate word for each orientation:

  • Members oriented front-to-rear: Longitudinal members
  • Members oriented left-to-right: Lateral members
  • Members oriented top-to-bottom: Vertical members

However, I'm stumped for one of the words when it comes to location:

  • Members located on the front or rear: End members
  • Members located on the left or right: Side members
  • Members located on the top or bottom: ??? members

Let me give a few usage examples. These are some examples of how we might name members in an assembly:

  • Vertical Side Flange (a vertical flange located on the sides)
  • Vertical End Flange (a vertical flange located on the ends)
  • Lateral End Flange (a lateral flange located on the ends)
  • Lateral ??? Flange (a lateral flange located on the top and bottom)
  • Longitudinal Side Flange (a longitudinal flange located on the sides)
  • Longitudinal ??? Flange (a longitudinal flange located on the top and bottom)

Another way to describe the positions is using the "plural" sense:

  • The longitudinal extremes are the "Ends"
  • The lateral extremes are the "Sides"
  • The vertical extremes are the... ???

As a usage example, we also might put a note to the following effect on a drawing:

  • "Repeat on both sides"
  • "Repeat on both ends"
  • "Repeat on both ...???"

Ideally, I'm looking for a word that can work in both singular plural and contexts, like "end/ends" and "side/sides" do.

We have such fitting words for the left-to-right and front-to-back extremes of something... I find it hard to believe that the English language has no fitting word for the vertical extremes of something. If it really doesn't, I would be strongly in favor of making up one...

  • Possible Duplicate Generic for top and bottom (Note: 'vertices' are the apexes or corners.)
    – Nigel J
    Commented Sep 5, 2018 at 20:29
  • 2
    Would Surface work? Commented Sep 5, 2018 at 20:34
  • @NigelJ thanks for pointing me to a similar post. I did find several posts with a similar question but none of them had the same engineering-context nuance that I'm looking for, or they had answers that don't work for my needs (like "vertical").
    – Sigenes
    Commented Sep 5, 2018 at 20:38
  • 5
    I'm not sure you'll find such a term. In most applications, top and bottom need to be treated very differently than one another (because gravity), whereas "sides" and "ends" are much more likely to be interchangeable. Think "ceiling and floor" or "roof and foundation" vs walls. Top-and-bottom symmetry is rare enough that the most common term for the two together is probably just "top and bottom".
    – 1006a
    Commented Sep 5, 2018 at 23:44
  • 3
    Possible duplicate of Is there a word like "sides" that means "top or bottom"? Commented Sep 6, 2018 at 1:23

4 Answers 4


You want words such as "sides" and "ends" to refer to absolute directions. But your readers might not understand them like that. Often, "sides" refers to the largest-area pair of opposite surfaces, and "ends" to the smallest-area pair. For example, if something is long left to right, but narrow and thin, you might talk of its left end and right end.

In your situation if the back surface is so long compared to its width that there's no danger of the user mistaking one sort of flange for the other sort, you could describe the longer two as side flanges and the shorter two as end flanges. Not because "end" specifically means top and bottom, but because "sides" are longer than "ends".

But to judge from your diagram the back surface looks almost square to me, and I fear that a user might think of the member as having four sides/edges and needing four side flanges. I'd favour being clear even if this means using more words. For example give instructions for the bottom horizontal flange, and then say attach the top horizontal flange similarly.


Planes, the top plane and bottom plane. Technically all the sides of a cube are planes.


How about ‘upper and lower members’?


Top and Bottom can be though as the upper and the lower layer of something..

  1. The top floor of the building caught fire first.
  2. A ground floor is usually the bottom floor of the building.
  3. Write "Happy Birthday" on the top of the cake.
  4. Let us get to the bottom of that issue.
  • Do you have an answer to the question?   Please do not respond in comments; edit your answer to make it clearer and more complete. Commented Oct 6, 2018 at 2:18

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