Source : Webster's Revised Unabridged Dictionary (1913)

Stupid \Stu"pid\, a. [L. stupidus, fr. stupere to be stupefied:
   cf. F. stupide.]
   1. Very dull; insensible; senseless; wanting in
      understanding; heavy; sluggish; in a state of stupor; --
      said of persons.

            O that men . . . should be so stupid grown . . . As
            to forsake the living God!            --Milton.

            With wild surprise, A moment stupid, motionless he
            stood.                                --Thomson.

   2. Resulting from, or evincing, stupidity; formed without
      skill or genius; dull; heavy; -- said of things.

            Observe what loads of stupid rhymes Oppress us in
            corrupted times.                      --Swift.

   Syn: Simple; insensible; sluggish; senseless; doltish;
        sottish; dull; heavy; clodpated. -- {Stu"pid*ly}, adv.
        -- {Stu"pid*ness}, n.

Source : WordNet®

stupidly
     adv : in a stupid manner; "he had stupidly bought a one way
           ticket" [syn: {doltishly}, {without thinking}]