Colloquial

 I have sometimes used the word colloquial to describe words on this blog. I should explain that colloquial does not mean slang.   

 

Slang is a kind of language occurring chiefly in casual and playful speech, made up typically of short-lived coinages and figures of speech that are deliberately used in place of standard terms for added raciness, humour, irreverence, or other effect; language peculiar to a group; argot or jargon.

Colloquial is often assumed to mean slang but it doesn't.  It simply means as used in a conversational sense; used in ordinary conversation; not formal or literary. Even a look at its synonyms yields ‘everyday’, ‘common’, and ‘idiomatic’ but not slang.  Colloquialisms are therefore perfectly acceptable in conversation whereas slang may or may not be.

Humongous

 
Humongous / humungous is a (slang?) term meaning of a very large size. Nowadays I find it hard to differentiate between what is slang and what is not. Slang is defined as informal language consisting of words and expressions that are not considered appropriate for formal occasions; often vituperative or vulgar. There is nothing vituperative or vulgar about humungous and it seems to be creeping into our formal language so perhaps it isn't slang. Who decides? The answer, I suppose lies with the compilers of the Oxford English Dictionary. If a word makes it into the OED it can be said to have arrived in the language and no longer be slang. I don't have an up-to-date OED so I'm not sure about humongous.