ARTICULAR is a 9 letter word that starts with A.

1. \Ar*tic"u*lar\, a. [L. articularis: cf. F.
   articulaire. See {Article}, n.]
   Of or pertaining to the joints; as, an articular disease; an
   articular process.
   
   

2. \Ar*tic"u*lar\, Articulary \Ar*tic"u*la*ry\, n.
   (Anat.)
   A bone in the base of the lower jaw of many birds, reptiles,
   amphibians, and fishes.