through, across

Quick Summary

Prefixes are key morphemes in English vocabulary that begin words. A fair number of English vocabulary words contain the prefix dia-, which means “across.” Examples using this prefix include dialogue, diagonal, and diabetes. An easy way to remember that the prefix dia- means “across” is through the word diameter, for the diameter of a circle is the measurement “across” it.

A Dialogue About "Dia-"

Prefixes are key morphemes in English vocabulary that begin words. The Greek prefix dia- means “across;” today we will have a one-sided dialogue to bring that point “across” to you!

Have you ever had a teacher who had a different dialect than yours? A dialect allows one person to speak “across” to another of a similar culture or region, but can be hard to understand if the two people don’t speak the same regional language. Imagine a teacher with a pronounced dialect teaching you about different polygons. He might talk about diagonals, or those lines “across” rectangles, reaching from one corner to another. He might also try to teach you about the diameter of a circle, or the measurement “across” the entire circle through its midpoint. Imagine that the dialect of the teacher was so confusing that it was diametrically opposed to your learning the material, that is, fully “across” from where it should be! Luckily in math many diagrams can be used, or figures written “across” a textbook page to give an example of a concept; these diagrams would give visual representations of diameters or diagonals, perhaps alleviating difficulties of the dialect!

Do you remember King Azaz, the king of Dictionopolis from Norton Juster’s book The Phantom Tollbooth? I always found it curious that there was no mention of a Queen of Dictionopolis, who would have worn a diadem, or crown bound “across” her head. She might also have worn a necklace sporting diaphanous diamonds, so clear that light could shine “across” and therefore “through” them. Let’s pretend that, unlike King Azaz, who only deals with the current meanings of words, Queen Zaza is interested in the diachronic definitions of words, that is, how their meanings change “across” time. Imagine having a dialogue with her, or a speaking “across” from her to you, in which she tells you the history of the word “nice,” mentioning that it used to mean “stupid” or “ignorant”! Perhaps Queen Zaza’s mission in life is to follow this diaspora of the different expired meanings of words, that is, their scattering “across” the world, thus explaining her absence.

No more of this one-sided dialogue! Now you can use the English prefix dia- with confidence in a true, two-person dialogue!

  1. dialect: a variant language that allows a speaking “across” from one person to another
  2. diagonal: line “across” a rectangle from one corner to another
  3. diameter: measurement “across” a circle through its midpoint
  4. diametrically: fully “across” from something else
  5. diagram: figure written “across” a page to illustrate a concept or information of some kind
  6. diadem: a crown worn “across” a ruler’s head
  7. diaphanous: of light shining “across” or “through” a clear material
  8. diachronic: of going “across” time
  9. dialogue: a speaking “across” between two people
  10. diaspora: a scattering “across” the world


  • diaspora

    A diaspora is a voluntary or forced movement of an ethnic people who permanently relocate in areas remote from their homeland.

  • diorama

    A diorama is a scene, reproduced in three dimensions, that places objects and figures in front of a painted background.

  • dialectic

    Dialectic is a dialogue between two people who present logical arguments in order to persuade each other of the truth of their opinion; during this interchange, the debaters arrive at a truth, which often involves parts of each debater's opinion.

  • diaphanous

    A diaphanous cloth is thin enough to see through.

  • diabolical

    If you say something is diabolical, you are emphasizing that it is evil, cruel, or very bad.

  • dialect

    A dialect is a form of a standard language, such as English, that has some differences in vocabulary, grammar, and pronunciation.

Related Roots

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