The Free On-line Dictionary of Computing (30 December 2018):

LL

    A class of language grammars, which can
   be parsed without backtracking.  The first L stands for
   Left-to-right scan, the second for Leftmost derivation.

   Often found in the form LL(k) where k is the number of
   tokens of look-ahead required when parsing a sentence of
   the language.  In particular, LL(1) is a fairly restrictive
   class of grammar, but allows simple top-down parsing
   (e.g. recursive-descent) to be used without wasteful
   backtracking.  A number of programming languages are LL(1)
   (or close).

   (1995-10-30)