The bound morpheme non is the negator for life-threatening here, so 'life-threatening' is more coherent.
This does not come across with nonlife-threatening, which would seem to imply a.
Is the hyphen that we often see in words such as non-zero, non-trivial, etc.
In case the answer is negative, is there any rule of thumb on which one may rely in order to recall whe
Does non- prefixed to a two word phrase permit another hyphen before the second word?
If i want to refer to an entity which is defined as the negation of another entity by attaching non- it.
The usage of a non-breaking space is explained in a wikipedia article under non-breaking spaces and controlling line breaks and below in items 1 and 5:
It is advisable to use a non-breaking.
Except non is not an english word, it is a prefix of latin origin.
Which is why american style manuals will always ask you to merge it with the subsequent word, without a hyphen.