What's in a word?

In a world that’s becoming more inclusive and understanding of diversity comes the new importance of understanding etymology and the origins of certain words.
 
Put simply – think about what you say before you say it…
 
This has been drawn to my attention a couple of times in recent months, both times by mums with neuro-diverse children. (Now there’s an expression – neuro diverse – that wouldn’t have been dropped into casual conversation until very recently.)
 
And both times, these mums called out the use of particular words as being essentially offensive.
 
The words? Loony and cretin. And looking at them there, in all their bald glory, of course they’re offensive. They’re used as insults, right? 
 
The word “cretin” is often used as a synonym for idiot but if you look into its background, you’ll find that “cretinism” was originally another name for those suffering congenital iodine deficiency syndrome, a medical condition present at birth, marked by impaired physical and mental development.
 
Of course, it would have been the condition’s mental impairments that led to “cretin” being used interchangeably with stupidity or idiocy – itself, at heart, an incredibly offensive attitude. Cretin, idiot, moron… these are all ableist slurs. 
 
As for loony – this one elicited much more of a discussion over on a certain social media platform. It’s especially an issue up here in Scotland, where the “loony dook” is an annual event. This sees hardy (foolish?) souls launch themselves into the sea on New Year’s Day – on the East Coast no mean feat, since the ocean is the North Sea. 
 
And the implication there is much clearer – the sort of person who swims in Scottish seas in the depth of winter is a “loony”. A lunatic. 
 
Many of the responses to the mum drawing attention to this, though polite, essentially shouted her down. It wasn’t meant as an insult, they said. It was a harmless joke. And, in this context, that might be true.
 
But loony is still an insult. And using it so casually in an otherwise harmless context is only normalising the insult, not weakening the word. It reinforces the word loony as an indicator of someone’s reduced mental stability – and thereby reinforces mental ill health as something that should be stigmatised.
 
Remember when the National Spastics Society changed its name to Scope? When the word for a particular condition (in their case cerebral palsy) becomes buried in our everyday lexicon as an insult, perhaps it should be abandoned altogether.
 
So, what do you think? Is a word harmless when its user doesn’t mean to be rude? Or are certain words just intrinsically… offensive?