# What are the differences between the words "QUASI", "HYPER", and "PSEUDO"?

As an opening our question, briefly consider the following three examples of mathematical terminology:

What are the differences between the words "QUASI", "HYPER", and "PSEUDO"?

Informally, a quasi-sphere is like a sphere, but different in a few different ways.

Likewise, a pseudo-sphere is like a sphere, but different from an actual sphere.

I am trying to understand the distinctions between the following three words...

1. Hyper

2. Quasi

3. Pseudo

We seeking an explanation which uses specific examples, and is not overly general.

If you do not desire to use the mathematical examples of quasi-spheres, pseudo-spheres, and hyper-spheres, the consider the following categories ...

### The category of all letters used in Written English:

defined, in this case, to be the set of all 52 letters large or small (`ABC`...`XYZ`...`abc`...`xyz`)

### The lowercases

the set of all 26 small lowercase letters (`abc`...`xyz`)

### The uppercases

The set of all 26 big uppercase letters (`ABC`...`XYZ`)

### The digits

set of all 10 arabian numerals or numeric (`0123456789`)

### The specials

The set of all 31 special characters from ASCII

`!"#\$%&'()*+,-./:;<=>?@[]^_`{|}~`

Note that lowercase letters are a sub-category of the set of all letters.

Does that mean that the letters are quasi-lowercase?

How would the words quasi, hyper, and pseudo be represented in set-theory?

• (A subset of B)?
• (A subset of C) and (B subset of C) and (B disjoint from C)?

What is the distinctions between the following three words...

1. Hyper

2. Quasi

3. Pseudo

• In math usage, you are trying to evoke 1. not-quite a sphere, 2. over-and-above a sphere, hence generalized sphere, 3. Fake sphere. So you might use a circle for 1, S³ for 2, and an ellipsoid for 3. Commented Apr 8 at 20:05
• Of course the strict technical definitions are quite different, the ones linked. Commented Apr 9 at 5:51

In Latin, quasi is a contraction of quam sī, "as if".

Assimulabo, quasi nunc exeam.
I'm going to pretend as if I'm just leaving.

With a noun, it tends to mean "almost".

quasi una aetas erat.
…it was almost a whole generation.

Hyper is not Latin but Greek, and means "over" or "above". Usually in a literal sense of position:

…στέρνον ὑπὲρ μαζοῖο,
[and hit him with a spear] right in the chest, above the nipple

But it can also mean "exceeding" or "beyond".

…ὑπὲρ τὸν ἀλαθῆ λόγον
…going beyond the true word

Pseudo is similarly not Latin but Greek, and means "to lie" or "to deceive".

ἔψευσας φρενῶν Πέρσας.
You have deceived the minds of the Persians.

• Not an expert in Greek (or Latin) but isn't there a typo in "ἔψευσας"? I would expect to see a "delta", not "sigma".
– tum_
Commented Apr 8 at 10:17
• @tum_ No, it's the aorist form. Verbs, like in English, change depending on the tense.
– cmw
Commented Apr 8 at 10:59
• @tum_ You can read full conjugation table here. Commented Apr 9 at 0:44
• In English usage, however, isn't "pseudo" used more like "false" or "fake" rather than any sort of verb? Commented Apr 9 at 19:58
• @SoronelHaetir Absolutely. But since the question was asked here, I'm focusing on the Latin and Greek meanings.
– Draconis
Commented Apr 9 at 20:12