Definition of left-branching in US English:

left-branching

adjective

Linguistics
  • Of a language, sentence, etc.: characterized by dependants which successively precede their heads (and which, in a parse tree representing the connection between main and subordinate units, branch successively towards the left).

noun

Linguistics
  • The fact of having dependants which successively precede their heads; the technique of organizing syntactic elements in this way.

Origin

1960s; earliest use found in Noam Chomsky (b. 1928), linguist, philosopher, and political activist. From left + branching.