The omitted sense is of TIMES (as distinct from the plural of
TIME, a period of time listed as [500] and [600]) illustrated
in the arithmetical expression 3 X 2 = 6 (read: three times two
equal six).
[4100] many a time, [4800] time after time and [4900] are
idiomlike realizations of this sense/use of the count noun TIME
more commonly used in the plural than in the singular (every,
next,first, last or ordinal + time or in a compound adjective, as
in your (30).
This interpretation tallies with the entry TIME in "The General
Service List" of M. West , Longman.1953:522 (based on the OED).
Also, Latin, French, Spanish, German and Hebrew have differentt
words as translation equivalents of these two senses (count and
non-count) of TIME.
Thus, I would not agree with Rebecca Wheeler's alignment of
[4100], [4800] and [4900] with [300] summer time and [400]
a long time etc., but I do support her suggestion that "attention
to the phrasal structure of collocations can point the way to
syntactic generalizations that may prove useful in organizing a
dictionary entry".(E-mail of 11 May)
Is Longman's Dictionary of Common English an MRD?
Best wishes
Nina Devons