Glib

1. readily fluent, often thoughtlessly, superficially, or insincerely so: a glib talker; glib answers.
2. easy or unconstrained, as actions or manners.
3. Archaic. agile; spry.
[Origin: 1585–95; cf. obs. glibbery slippery (c. D glibberig)] —Related forms
glibly, adverb
glibness, noun
—Synonyms 1. talkative, loquacious; facile, smooth.

1. a. Performed with a natural, offhand ease: glib conversation.
b. Showing little thought, preparation, or concern: a glib response to a complex question.
2. Marked by ease and fluency of speech or writing that often suggests or stems from insincerity, superficiality, or deceitfulness. [Possibly of Low German origin; see ghel-2 in Indo-European roots.] glib'ly adv., glib'ness n.
Synonyms: These adjectives mean being, marked by, or engaging in ready but often insincere or superficial discourse: a glib denial; a slick commercial; a smooth-tongued hypocrite.

1593, possibly shortening of obsolete glibbery "slippery," from Low Ger. glibberig "smooth, slippery," from M.L.G. glibberich, from glibber "jelly."

adjective
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"
3. artfully persuasive in speech; "a glib tongue"; "a smooth-tongued hypocrite"