What is the word for the point where two lines come together, if that point is at the bottom of the whole?

For example, in a cone (so this isn't exclusively lines), pointed down, what would you call the point?

Vertex is a possibility as it means

• each angular point of a polygon, polyhedron, or other figure.

• a meeting point of two lines that form an angle.

However, it also means

• the highest point; the top or apex

which is in fact the opposite of the meaning I seek, and could lead to confusion.

Nadir, as the lowest point, could work but it makes no reference to anything coming together and, I believe, only used figuratively except for in reference to astronomy.

Use in a sentence:

• We need to put a gutter at the ---- of the (inverted) roof, where the two sides slope down to each other.

• The font-designer recommended that his student make the capital M's ---- sharper.
(Note: I choose M rather than V because the lower angle of the M is not in fact the lowest part of the M—it is not the base or the bottom. It's primary identity is as a vertex, except that vertex also indicates apex.)

Edit and possible answer:

Juncture, a place where things join

which carries no meaning of top.

All definitions from NOAD.

  • What's wrong with "lowest point"?
    – TrevorD
    Mar 15, 2017 at 23:42
  • Antonyms of "apex": Base, bottom, nadir.
    – Hot Licks
    Mar 15, 2017 at 23:45
  • 3
    But for your roof situation the usual term is "valley".
    – Hot Licks
    Mar 15, 2017 at 23:46
  • @HotLicks While those are the antonyms of apex in any thesaurus, they make no reference to coming to a point
    – Unrelated
    Mar 15, 2017 at 23:50
  • perhaps 'rock-bottom' Mar 16, 2017 at 3:08

3 Answers 3


Consider valley:

2 :  a low point or condition

3 b :  the place of meeting of two slopes of a roof that form on the plan a reentrant angle

The term does invoke metaphorical imagery, but is also a roofing term as indicated by the definition.

Here is a description of a butterfly roof using the term:

butterfly roof (sometimes called a V roof or London roof) is a form of roof characterised by an inversion of a standard roof form, with two roof surfaces sloping down from opposing edges to a valley near the middle of the roof.

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  • I've added a second example to make the word-request more general because I am not only looking for the point where two surfaces come together.
    – Unrelated
    Mar 16, 2017 at 6:07
  • I provided two definitions for valley, and the first of the two satisfies both examples.
    – jxh
    Mar 16, 2017 at 6:20
  • I would consider a slope a surface. I would also notice that the definition refers specifically to roofs.
    – Unrelated
    Mar 16, 2017 at 16:33
  • a low point or condition
    – jxh
    Mar 16, 2017 at 16:46
  • @jxh - For your roof example "valley" is definitely the correct term. This is the term used by roofers and architects and the like. Your other example is screwed up, so I can't tell what it should be.
    – Hot Licks
    Mar 16, 2017 at 17:36


  • the bottom part of an object, on which it rests, or the lowest part of something.

(Cambridge Dictionary)

  • We need to put a gutter at the base of the (inverted) roof, where the two sides slope down to each other.


According to MW: A depression is "a place or part that is lower than the surrounding area"

If you don't want to use nadir, depression is the word that comes first to mind. As previously stated here, you can also use base or bottom, but I think this serves your sentence best.

  1. We need to put a gutter at the depression of the (inverted) roof, where the two sides slope down to each other.
  • While depression gives the ... impression, at least to me, of a more rounded low point, I appreciate this suggestion
    – Unrelated
    Mar 16, 2017 at 6:08

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