Regarding, re.
Abbreviation of "recursively enumerable"; the class of decision problems for which a 'yes' answer can be verified by a Turing machine in a finite amount of time.
Unsupported and liable to be turned or taken in flank.
In the surrounding ambience.
Not in a fixed or stable position; unsettled; up in the air.
Prevalent without traceable origin or authority.
In the generally prevailing feeling, idea, atmosphere, or mood.