The Collaborative International Dictionary of English v.0.48:

Larch \Larch\ (l[aum]rch), n. [Cf. OE. larege (Cotgrave), It.
   larice, Sp. larice, alerce, G. l[aum]rche; all fr. L. larix,
   -icis, Gr. la`rix.] (Bot.)
   A genus of coniferous trees, having deciduous leaves, in
   fascicles (see Illust. of Fascicle).

   Note: The European larch is Larix Europ[ae]a. The American
         or black larch is Larix Americana, the hackmatack or
         tamarack. The trees are generally of a drooping,
         graceful appearance.
         [1913 Webster]

WordNet (r) 3.0 (2006):

larch
    n 1: wood of a larch tree
    2: any of numerous conifers of the genus Larix all having
       deciduous needlelike leaves [syn: larch, larch tree]

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

Larch

   The Larch Project develops aids for formal specifications.
   Each Larch specification has two components: an interface
   containing predicates written in the LIL (Larch Interface
   Language) designed for the target language and a 'trait'
   containing assertions about the predicates written in LSL,
   the Larch Shared Language common to all.

   ["The Larch Family of Specification Languages", J. Guttag et
   al, IEEE Trans Soft Eng 2(5):24-365 (Sep 1985)].