The Collaborative International Dictionary of English v.0.48:

Glib \Glib\ (gl[i^]b), a. [Compar. Glibber (gl[i^]b"b[~e]r);
   superl. Glibbest (gl[i^]b"b[e^]st).] [Prob. fr. D.
   glibberen, glippen, to slide, glibberig, glipperig, glib,
   slippery.]
   [1913 Webster]
   1. Smooth; slippery; as, ice is glib. [Obs.]
      [1913 Webster]

   2. Speaking or spoken smoothly and with flippant rapidity;
      fluent; voluble; as, a glib tongue; a glib speech.
      [1913 Webster]

            I want that glib and oily art,
            To speak and purpose not.             --Shak.

   Syn: Slippery; smooth; fluent; voluble; flippant.
        [1913 Webster]

The Collaborative International Dictionary of English v.0.48:

Glib \Glib\, v. t.
   To make glib. [Obs.] --Bp. Hall.
   [1913 Webster]

The Collaborative International Dictionary of English v.0.48:

Glib \Glib\, n. [Ir. & Gael. glib a lock of hair.]
   A thick lock of hair, hanging over the eyes. [Obs.]
   [1913 Webster]

         The Irish have, from the Scythians, mantles and long
         glibs, which is a thick curied bush of hair hanging
         down over their eyes, and monstrously disguising them.
                                                  --Spenser.
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         Their wild costume of the glib and mantle. --Southey.
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The Collaborative International Dictionary of English v.0.48:

Glib \Glib\, v. t. [Cf. O. & Prov. E. lib to castrate, geld,
   Prov. Dan. live, LG. & OD. lubben.]
   To castrate; to geld; to emasculate. [Obs.] --Shak.
   [1913 Webster]

WordNet (r) 3.0 (2006):

glib
    adj 1: marked by lack of intellectual depth; "glib
           generalizations"; "a glib response to a complex question"
    2: having only superficial plausibility; "glib promises"; "a
       slick commercial" [syn: glib, pat, slick]
    3: artfully persuasive in speech; "a glib tongue"; "a smooth-
       tongued hypocrite" [syn: glib, glib-tongued, smooth-
       tongued]

Moby Thesaurus II by Grady Ward, 1.0:

86 Moby Thesaurus words for "glib":
   Ciceronian, Demosthenian, Demosthenic, Mickey Mouse, Tullian,
   all jaw, articulate, bland, buttery, candid, casual, chatty, clear,
   communicative, conversational, cushy, disarming, easy, easy as pie,
   effortless, effusive, eloquent, expansive, facile, facund,
   fair-spoken, felicitous, fine-spoken, flip, fluent, fluid, frank,
   fulsome, gabby, garrulous, gassy, gossipy, gregarious, gushy,
   honey-mouthed, honey-tongued, ingratiating, light, long-winded,
   loquacious, multiloquent, multiloquious, newsy, nonchalant,
   nothing to it, oily, oily-tongued, overtalkative, painless, plain,
   prolix, ready, silver, silver-tongued, simple, simple as ABC,
   slick, smooth, smooth-spoken, smooth-tongued, smug, soapy,
   sociable, soft, soft-spoken, spellbinding, straightforward, suave,
   suave-spoken, superficial, talkative, talky, unburdensome,
   uncomplicated, unctuous, verbose, vocal, vocative, voluble,
   well-spoken, windy