I lighted upon the word cretinosity today. The Oxford Dictionary of English Idioms has a sentence:
If you read the English media or watch the cretinosities of television, you would think that the country is going to the dogs.
Google searches seem to link the usage of this word to a range of facetious websites, which makes it difficult to tell whether it is a real word.
What does it mean? Where did it come from?
To address one of your questions, the formation of cretinosity is made by adding the common -osity suffix to "cretinous". This is a common enough thing for words ending in -ous, compare:
scrupulous - scrupulosity
virtuous - virtuosity
luminous - luminosity
curious - curiosity
generous - generosity
So that's for morphological explanation of the suffix, and the original adjective (cretinous) it is based on.
So what is cretinous?
1.a person suffering from cretinism.
dictionary.com
So what is cretinism?
Cretinism is a condition of severely stunted physical and mental growth owing to untreated congenital deficiency of thyroid hormone (congenital hypothyroidism) usually owing to maternal hypothyroidism.
Cretinism
So why in your example does it use "having to do with cretinism" with television programs?
cretin
n. (often offensive)
2. A person considered to be foolish or unintelligent.
American Heritage Dictionary
So the word came to connote someone or something stupid or foolish. Note this is a common phenomenon, that of using words to describe physical or mental impairments as terms of ridicule or abuse. Words like "spastic" and "retard" are/were medical conditions that, because of becoming common vulgar terms of offence, have often been the subject of what Steven Pinker calls the euphemism treadmill, keeping up with changes in social perception of insulting words, the result being that words change to more euphemistic ones.
Finally, if in your question you meant what the original etymology of cretin or cretinism is:
etymonline.com claims it's from:
Vulgar Latin *christianus "a Christian," a generic term for "anyone"
etymonline.com
American Heritage Dictionary claims it's from:
person with cretinism (formerly common in Alpine valleys because of insufficient iodine in the local diet), from Vulgar Latin *christiānus, Christian, human being, poor fellow
American Heritage Dictionary
And so too do many dictionaries. However Wikipedia says the etymology is uncertain. It gives the most common hypotheses as the ones I've given above. Additionally it give others:
From creta, Latin for chalk, because of the pallor of those affected.
From cretira, Grison-Romanche creature, from Latin creatus.
From cretine, French for alluvium (soil deposited by flowing water), an allusion to the affliction's suspected origin in inadequate soil.
Cretinism etymology
Cretinosity is a noun that is somewhat whimsically or playfully derived from the adjective cretinous by replacing the adjective ending -ous with the noun ending -osity. There are a number of -ous adjectives paired with -osity nouns in English, but this correspondence is not very productive, so coining new -osity words like cretinosity is a bit unusual and comes across in this context as a minor bit of wordplay.
For the meaning of the plural noun cretinosities in this sentence, compare the use of the noun monstrosities: just as monstrosities means "things (or people) that are monstrous", cretinosities would be expected to mean "things (or people) that are cretinous".
The Collins English Dictionary tells us:
If you describe someone as cretinous, you think they are very stupid.
So "If you read the English media or watch the cretinosities of television, you would think that the country is going to the dogs" could be summarized as "If you read the English media or watch the [very stupid things/people that are on television], you would think that the country is going to the dogs."
You can find the etymology of cretinous and the noun it is based on, cretin, in the dictionary, so I won't go over that here.
Cretinosity is an affected cretinism, in that the suffix, osity transforms adjectives into nouns. So one may surmise that it is a kind of mockery of cretinism, which is to say a mockery of physical stunting and mental retardation, which in the case of media and television, may be either real or imagined.
