Glib means fluent and easy, but shallow and insincere. A glib answer, glib assurances, sound glib.
It is always a criticism, and what it condemns is the smoothness: a glib reply came too easily to have cost the speaker anything. The word first meant slippery, and the modern sense is that image applied to talk.
1adjectiveglibFluent and easy, but shallow and insincere.
“When I asked why he was late again, he gave a glib excuse and changed the subject.”
glib is a quality.
A shortening of an older word meaning slippery, from Low German or Dutch glibberig.
Dutch
glibberig — slippery
Low German
glibberig — slippery
English, today
glib
A shortening of either obsolete English glibbery (“slippery”) or its source, Low German glibberig (“slippery”) / Dutch glibberig (“slippery”).
Etymology from Wiktionary, CC BY-SA