There's "primary", "secondary", "tertiary". What comes next (at "number 4")?

Sorry, I am not able to phrase this question any better, I hope it is clear from the context what I mean.

  • Wouldn't it be fit question for EL&U? Feb 27, 2014 at 13:56
  • Do you still have the link? I think that aspect is of interest for English speakers in general, not only to those who learn it. Feb 27, 2014 at 15:31
  • I always thought it was "everyone else", "etc" or, in the words of my boss "that other stuff that we'll never actually get to."
    – NotMe
    Feb 27, 2014 at 23:22
  • @ChrisLively Well, yeah, it is so a lot of times. I hit upon the need for this word due to ... computer memory. You see: RAM is primary memory, hard disk is secondary memory, optical disks, USB stick, etc. is tertiary memory. Most textbooks stop at this point, but I began wondering what should cloud storage be called? It seems wrong to club it together with tertiary memory for obvious reasons, so I needed something at "no. 4".
    – Masked Man
    Feb 28, 2014 at 2:58
  • Post-Tertiary ? Will that convey the case of a Hospital whihc is past Tertiary Care?
    – user37480
    Jul 8, 2016 at 3:30

1 Answer 1


The sequence may go on like...

primary, secondary, tertiary, quaternary, quinary, senary, septenary, octonary, nonary, and denary.

I'm not sure after tertiary, those words are commonly used though.

Source here

  • 2
    Thanks. I have heard those words before, but I thought they are only used for number systems (Unary, binary, ternary, quaternary, ...). Since the first three words in the "sequence" did not match, I thought there might be a different "sequence" for this! :)
    – Masked Man
    Feb 27, 2014 at 11:35
  • 3
    and 8-based number system I would call octal, not octonary. Compare to decimal instead of denary. So Maulik's names are not used for number systems, unless I am completely misinformed.
    – oerkelens
    Feb 27, 2014 at 11:55
  • 1
    You are not misinformed, but you did misinterpret my comment, or rather, I did not express it properly. What I had meant was, I did guess quaternary, but then asked this question because it was already "taken" by the number systems sequence. Uhm, something like that, but question is answered now so no problems. :)
    – Masked Man
    Feb 27, 2014 at 12:44
  • Secondary is 'second to use', 'second in row' etc., while 'binary' is 'system based on 2', so the Happy's sequence is something distinct. Feb 27, 2014 at 13:56
  • 1
    Only primary and secondary are used frequently in common speech. Tertiary might be used occasionally, quaternary only in certain subjects, terms beyond that, never.
    – rlms
    Jun 24, 2014 at 11:00

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