Real Dictionary

jab
countable noun: A jab is a sudden, sharp punch.
verb: If you jab one thing into another, you push it there with a quick, sudden movement and with a lot of force.

jab in American English
a quick thrust, blow, or punch
to poke or thrust, as with a sharp instrument
to poke, or thrust abruptly or sharply, as with the end or point of a stick
noun: a poke with the end or point of something; a sharp, quick thrust

jab in British English
noun: a sharp poke or stab
verb: to poke or thrust sharply