Articulation is the act of expressing something in a coherent verbal form, or an aspect of pronunciation involving the articulatory organs.
Articulation comes from the Latin word for "jointed" or "divided into joints." So it makes sense that the word's original definition described movement at a joint, as in the articulation of your fingers while you're typing. (The joints themselves can also be called articulations.) This noun also describes the act of joining things in such a way that makes motion possible.