Source : Webster's Revised Unabridged Dictionary (1913)

Tenuous \Ten"u*ous\, a. [L. tenuis thin. See {Thin}, and cf.
   {Tenuis}.]
   1. Thin; slender; small; minute.

   2. Rare; subtile; not dense; -- said of fluids.

Source : WordNet®

tenuous
     adj 1: having little substance or significance; "a flimsy excuse";
            "slight evidence"; "a tenuous argument"; "a thin plot"
            [syn: {flimsy}, {slight}, {thin}]
     2: having thin consistency; "a tenuous fluid"
     3: very thin in gauge or diameter; "a tenuous thread"