• The surface of the colony* is flat and rugged.
  • The surface of the colony* is not flat and rugged.

*(a colony of fungi)

Flat is in this case refers to the elevation of the colony. From the side view, it's flat, like a computer disc.

What is the opposite of flat, for this context? Is it non-flat?

  • 7
    flat and rugged could be considered antonyms, so I'm having trouble understanding your first example. But a colony of fungi that isn't "flat" might be considered "bumpy."
    – J.R.
    Dec 9, 2014 at 8:54
  • 1
    Perhaps this question would be better suited to biology SE since it is about colony morphology. Flat is used to describe the elevation of a colony. A colony could also be described as raised, umbonate or a number of other possibilities. Since there is more that one possible description, there really is no opposite of flat in this context. It would be best to describe the colony by what it is rather than what it is not.
    – canadianer
    Dec 9, 2014 at 9:33
  • For this specific usage it might be refering to "hairy" or "fuzzy" - but I agree with @can this may be better at biology.se Dec 9, 2014 at 9:39
  • 3
    Also, "not flat" can work. Sometimes "not <adjective>" is the best way to express something. I might say, "She's not rich," but that doesn't mean she's poor – it just means she isn't rich.
    – J.R.
    Dec 9, 2014 at 10:30
  • 1
    @canadianer: Right on. I have discovered it: ruf.rice.edu/~bioslabs/bios318/colony.htm
    – student
    Dec 9, 2014 at 15:06

5 Answers 5


There are too many antonyms to count! It depends on how you want to use the word:

  • The cola is not flat, it's bubbly.
  • The tire is not flat, it's full.
  • Her lecture was not flat, it was exciting.
  • His humor isn't flat, it's wry.
  • The earth isn't flat, it's round.
  • Business is not flat, it's booming.
  • That roof is not flat, it's sloped.
  • Our piano is not flat, it's sharp.
  • His feet are not flat, they're arched.
  • The tax scale isn't flat, it's graduated.
  • His denial of the allegations were not flat, they were wavering.

You made the classic "mistake" of asking for an antonym without furnishing a context! I'm guessing you had something more like this in mind:

  • The countryside isn't flat, it's hilly.

but that might not work near a valley.

  • 2
    It also depends on which aspect of flat you're looking to oppose; if you want to oppose all of them, then the only way, as you comment is to say not flat. Possible pairings are flat and rough, bumpy, curved, hilly, contoured, etc... As a side note calling a tyre full sounds odd to me; I'd call it inflated or pumped
    – jimsug
    Dec 9, 2014 at 14:44
  • Perhaps you should update the answer since a context has been furnished? Feb 17, 2015 at 16:54
  • @EsotericScreenName - I might have done that, had Maurice Reeves not furnished an excellent answer already (which I have upvoted). I really wish the OP would come back and accept that deserving answer.
    – J.R.
    Feb 17, 2015 at 16:58
  • Indeed, but this is currently the top voted answer and outscores Maurice's by more than a factor of three... Feb 17, 2015 at 17:03

If you're talking about the surface of a colony of fungus, and it is not flat, there are many different terms you could use based on the level of "not-flat-ness" (patent pending):

  • Rough - Think like the texture of sandpaper or jeans
  • Ribbed - Like corduroy pants
  • Varied - Like rolling hills. Areas are flat, and others sloped
  • Sloped - Like a round hill, or the top of a mushroom
  • Cracked - Has cracks in it
  • Creviced - Like cracked, but deeper
  • Undulating - Marked by steep rolling hills
  • Pockmarked - Filled with small holes, like a sponge
  • Fissured - Similar to cracked, but stronger
  • Craggy - Like the rocky face of a cliff
  • Cleft - Split in the middle, like a cleft chin
  • Mountainous - Mountains
  • Severe - Steep
  • Pitted - Like pockmarked, but deeper holes
  • Not flat - Exactly what it says, something's not flat.

They all have subtle meanings, implying different levels of "not-flat-ness."

Also, as others have pointed out, you would not usually say that something is both flat AND rugged. In English, rugged is typically used to amplify the adjective describing how unflat something is. So mountains are rugged, but a flat plains land probably wouldn't necessarily be, unless you're trying to imply that at first glance the prairie looked flat and easy to cross but it turned out not to be because it was full of danger.


I would go with:



The problem here is that asking for a generic antonym for "flat" is rather like asking for an antonym for "neutral" or "plain", or perhaps "silent" or "odorless" — they're all words that describe the absence of any features of a certain type, and so any informative antonym would need to describe which features are actually present.

Or, to misquote Leo Tolstoy: all flat surfaces are alike, but all non-flat ones are different.

That said, if you do really need a generic antonym for "flat", e.g. to present a binary choice between flat and non-flat, some possible choices could be:

  • "textured" (as suggested by BM-): Tends to imply the presence of small-scale variation; sometimes used as an antonym of "smooth", or as a milder near-synonym for "rough". Common in certain technical fields; for example, a graphic artist might describe the color of a surface as either flat/solid or textured.

  • "varied": A generic word for "not all the same". May be used synonymously with "textured", but with a slightly broader sense.

  • "elevated": An antonym of "flat" in a somewhat different sense than either "textured" or "varied". Could be applicable if "flat" is being used in a sense of "lying close to a surface".

  • "not flat": This really is the most generic possible antonym for "flat".

    In fact, many general English antonym pairs, like "colorful" / "colorless" or "visible" / "invisible", are of this type — the word "flat" just doesn't happen to have a regular suffix like "-ful" that could be inverted to "-less", and doesn't customarily accept a negative prefix like "un-" or "in-", so it has to be negated somewhat more awkwardly.

    (That said, *"unflat", while not a commonly used word in contemporary English, would certainly be an understandable construction. I'm not really advising you to use it, but you could do it and get the meaning across. "Non-flat", as I've used earlier, would be a somewhat better compromise.)

  • Excellent analysis. As a footnote, elevated (or raised) seems like what the O.P. was asking for in this case.
    – J.R.
    Dec 10, 2014 at 23:50

Possibly "textured" might work, if further description of the surface is not required.

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