The Collaborative International Dictionary of English v.0.48:

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.
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   2. Not deep in tone. [R.]
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            The sound perfecter and not so shallow and jarring.
                                                  --Bacon.
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   3. Not intellectually deep; not profound; not penetrating
      deeply; simple; not wise or knowing; ignorant;
      superficial; as, a shallow mind; shallow learning.
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            The king was neither so shallow, nor so ill
            advertised, as not to perceive the intention of the
            French king.                          --Bacon.
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            Deep versed in books, and shallow in himself.
                                                  --Milton.
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