[ra.chis] n, pl ra.chis.es also ra.chi.des [NL rachid-, rachis, fr. Gk rhachis; akin to Gk rhachos thorn, Lith razas dry twig, tine] (1842) 1: spinal column
2: an axial structure: as a (1): the elongated axis of an inflorescence (2): an extension of the petiole of a compound leaf that bears the leaflets b: the distal part of the shaft of a feather that bears the web