Source : Webster's Revised Unabridged Dictionary (1913)

Shallow \Shal"low\, a. [Compar. {Shallower}; superl.
   {Shallowest}.] [OE. schalowe, probably originally, sloping or
   shelving; cf. Icel. skj[=a]lgr wry, squinting, AS. sceolh, D.
   & G. scheel, OHG. schelah. Cf. {Shelve} to slope, {Shoal}
   shallow.]
   1. Not deep; having little depth; shoal. ``Shallow brooks,
      and rivers wide.'' --Milton.

   2. Not deep in tone. [R.]

            The sound perfecter and not so shallow and jarring.
                                                  --Bacon.

   3. Not intellectually deep; not profound; not penetrating
      deeply; simple; not wise or knowing; ignorant;
      superficial; as, a shallow mind; shallow learning.

            The king was neither so shallow, nor so ill
            advertised, as not to perceive the intention of the
            French king.                          --Bacon.

            Deep versed in books, and shallow in himself.
                                                  --Milton.