Source : Webster's Revised Unabridged Dictionary (1913)

Nonsensical \Non*sen"si*cal\, a.
   Without sense; unmeaning; absurb; foolish; irrational;
   preposterous. -- {Non*sen"si*cal*ly}, adv. --
   {Non*sen"si*cal*ness}, n.

Source : WordNet®

nonsensical
     adj 1: completely devoid of wisdom or good sense; "the absurd
            excuse that the dog ate his homework"; "that's a
            cockeyed idea"; "ask a nonsensical question and get a
            nonsensical answer"; "a contribution so small as to be
            laughable"; "it is ludicrous to call a cottage a
            mansion"; "a preposterous attempt to turn back the
            pages of history"; "her conceited assumption of
            universal interest in her rather dull children was
            ridiculous" [syn: {absurd}, {cockeyed}, {derisory}, {idiotic},
             {laughable}, {ludicrous}, {preposterous}, {ridiculous}]
     2: having no intelligible meaning; "nonsense syllables"; "a
        nonsensical jumble of words" [syn: {nonsense(a)}]