The Collaborative International Dictionary of English v.0.48:

Stammer \Stam"mer\ (st[a^]m"m[~e]r), v. t.
   To utter or pronounce with hesitation or imperfectly; --
   sometimes with out.
   [1913 Webster]

The Collaborative International Dictionary of English v.0.48:

Stammer \Stam"mer\, n.
   Defective utterance, or involuntary interruption of
   utterance; a stutter.
   [1913 Webster]

The Collaborative International Dictionary of English v.0.48:

Stammer \Stam"mer\ (st[a^]m"m[~e]r), v. i. [imp. & p. p.
   Stammered (-m[~e]rd); p. pr. & vb. n. Stammering.] [OE.
   stameren, fr. AS. stamur, stamer, stammering; akin to D. &
   LG. stameren to stammer, G. stammeln, OHG. stammal[=o]n,
   stamm[=e]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
   difficulty; to stutter.
   [1913 Webster]

         I would thou couldst stammer, that thou mightest pour
         this concealed man out of thy mouth, as wine comes out
         of a narrow-mouthed bottle, either too much at once, or
         none at all.                             --Shak.
   [1913 Webster]

WordNet (r) 3.0 (2006):

stammer
    n 1: a speech disorder involving hesitations and involuntary
         repetitions of certain sounds [syn: stammer, stutter]
    v 1: speak haltingly; "The speaker faltered when he saw his
         opponent enter the room" [syn: bumble, stutter,
         stammer, falter]