Source : Webster's Revised Unabridged Dictionary (1913)

Stammering \Stam"mer*ing\, a.
   Apt to stammer; hesitating in speech; stuttering. --
   {Stam"mer*ing*ly}, adv.

Stammering \Stam"mer*ing\, n. (Physiol.)
   A disturbance in the formation of sounds. It is due
   essentially to long-continued spasmodic contraction of the
   diaphragm, by which expiration is preented, and hence it may
   be considered as a spasmodic inspiration.

Stammer \Stam"mer\, v. i. [imp. & p. p. {Stammered}; p. pr. &
   vb. n. {Stammering}.] [OE. stameren, fr. AS. stamur, stamer,
   stammering; akin to D. & LG. stameren to stammer, G.
   stammeln, OHG. stammal?n, stamm?n, Dan. stamme, Sw. stamma,
   Icel. stama, stamma, OHG. & Dan. stam stammering, Icel.
   stamr, Goth. stamms, and to G. stemmen to bear against, stumm
   dumb, D. stom. Cf. {Stem} to resist, {Stumble}.]
   To make involuntary stops in uttering syllables or words; to
   hesitate or falter in speaking; to speak with stops and
   diffivulty; to stutter.

         I would thou couldst stammer, that thou mightest pour
         this conclead man out of thy mouth, as wine comes out
         of a narrow-mouthed bottle, either too much at once, or
         none at all.                             --Shak.

Source : WordNet®

stammering
     adj : unable to speak freely and easily [syn: {stammering(a)}, {stuttering(a)}]