Except non is not an english word, it is a prefix of latin origin In expressions in which figures and abbreviations (or symbols. Which is why american style manuals will always ask you to merge it with the subsequent word, without a hyphen
There seem to be three terms used by experts in the field My sense is to imply a minuscule chance, a slim chance, a small chance etc. However, the other two seem to be more commonly used in that context.
A similar word is thankful, which is rarely ever ascribed to any deity in particular in popular usage. This really depends on the example. Is this phrasing peculiar to american speakers or do british speakers use this expression too I hear and use this in ame frequently
