Source : Webster's Revised Unabridged Dictionary (1913)

Jab \Jab\, v. t. [Cf. {Job}.]
   To thrust; to stab; to punch. See {Job}, v. t. [Scot. &
   Colloq. U. S.]

Jab \Jab\, n.
   A thrust or stab. [Scot. & Colloq. U. S.]

Source : WordNet®

jab
     v 1: poke or thrust abruptly; "he jabbed his finger into her
          ribs" [syn: {prod}, {stab}, {poke}, {dig}]
     2: strike or punch quick and short blows
     3: stab or pierce; "he jabbed the piece of meat with his pocket
        knife" [syn: {stab}]
     [also: {jabbing}, {jabbed}]

jab
     n 1: a sharp hand gesture (resembling a blow); "he warned me with
          a jab with his finger"; "he made a thrusting motion with
          his fist" [syn: {jabbing}, {poke}, {poking}, {thrust}, {thrusting}]
     2: a quick short straight punch
     3: the act of touching someone suddenly with your finger or
        elbow; "she gave me a sharp dig in the ribs" [syn: {dig}]
     [also: {jabbing}, {jabbed}]