Source : Webster's Revised Unabridged Dictionary (1913)

Shirt \Shirt\, v. t. & i. [imp. & p. p. {Shirted}; p. pr. & vb.
   n. {Shirting}.]
   To cover or clothe with a shirt, or as with a shirt.
   --Dryden.

Shirt \Shirt\, n. [OE. schirte, sherte, schurte; akin to Icel.
   skyrta, Dan. skiorte, Sw. skjorta, Dan. ski["o]rt a
   petticoat, D. schort a petticoat, an argon, G. schurz,
   sch["u]rze, an argon; all probably from the root of E. short,
   as being originally a short garment. See {Short}, and cf.
   {Skirt}.]
   A loose under-garment for the upper part of the body, made of
   cotton, linen, or other material; -- formerly used of the
   under-garment of either sex, now commonly restricted to that
   worn by men and boys.

         Several persons in December had nothing over their
         shoulders but their shirts.              --Addison.

         She had her shirts and girdles of hair.  --Bp. Fisher.

Source : WordNet®

shirt
     n : a garment worn on the upper half of the body

shirt
     v : put a shirt on