• (a.) Capable of, or pertaining to, flection or inflection.
Flec'tion·al adjective Capable of, or pertaining to, flection or inflection. « A flectional word is a phrase in the bud.» Earle. 
flection, flexion, flectional 1. Deviation from a straight or normal course. 2. The act of bending a joint or limb in the body by the action of flexors; the resulting condition of being bent. 3. A part that is bent. 4. The act of bending. 5. The state of being bent. 6. A bend; a bent part.