How do you write the word semi transparent (meaning partially transparent)?

  1. semitransparent
  2. semi-transparent
  3. semi transparent

I found each of them on the Internet and none of them in my English dictionary.

3 Answers 3


The British National Corpus has 4 mentions of semitransparent, and none of either semi-transparent or semi transparent.

Wiktionary has an entry for semitransparent, but not for semi-transparent. Merriam-Webster has an entry for semitransparent and says that the first known use was in 1731.

(Google seems to be rather unreliable here: searching for "semi transparent" matches semitransparent and semi-transparent, and vice versa.)

  • I tried to find the corresponding numbers from the Corpus of Contemporary American English, but got heartily tired of fighting with the interface and gave up.
    – Marthaª
    Oct 22, 2010 at 19:27

The American Heritage Dictionary Fourth Edition includes “semitransparent”.

“semi-”, in this case, is being used a prefix rather than a word. Because of this, I would not use “semi transparent”.

Regarding “semi-transparent”, my understanding is that the hyphen tends to be dropped and the word elements combined to form a derivative word according to how common the combination is. Therefore, if I had not been able to locate it in the dictionary, then I would likely have used the hyphenated prefix.


I know "semi-transparent" and "semitransparent" are both used, but normally I see it written as "translucent". Anyway, unless if you're writing a formal document, it doesn't matter because everyone will get it, and I wouldn't look at a dictionary because language changes faster than dictionary publications.

  • 1
    “translucent” indicates distortion of the partially-blocked image, while “semitransparent” does not. Oct 22, 2010 at 16:12
  • 2
    @Jeffrey: I've never heard that meaning of "translucent" and my online dictionary search finds no such meaning. To me, translucent means "light goes through". Do you have a source for your definition? In my English Translucent and Semitransparent are synonyms. Oct 22, 2010 at 19:02
  • The American Heritage Dictionary says "1. Transmitting light but causing sufficient diffusion to prevent perception of distinct images." I originally put "connotes" on my comment, but after I read the definition, I changed it to "indicates". Oct 22, 2010 at 19:07
  • 1
    @Jeffrey: I'd say "diffusion" is different than "distortion" Oct 25, 2010 at 14:29
  • @Mr. Shiny and New - I would say that distortion includes diffusion. And though you may ding me for lack of specificity in my comment, it is clear that “translucent” is not the same as “semi-transparent”. Oct 25, 2010 at 20:50

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