KeithS mentioned some possibilities but seems to have blithely skipped over one of the best modifiers, vanishingly, as found in phrases like vanishingly small, vanishingly rare, and vanishingly probable. For examples like the following, see Edwin Ashworth's answeranswer to What word is used to describe an event that will never occur?What word is used to describe an event that will never occur?:
The probability that they coincide by chance is vanishingly small," said coauthor Alan Linde, also of Carnegie.
'The number of complaints which are substantiated is vanishingly small....' (Huddersfield Daily Examiner)
(Ashworth calls the latter an example of misuse, as no fixed finite number can be vanishingly small.)
