-ˌlizəm noun
( -s )
1.
a. : an expression considered more appropriate to familiar conversation than to formal speech or to formal writing
slang words frequently rise to the rank of colloquialisms — G.L.Kittredge
b. : an expression belonging to local or regional dialect — not used technically
2. : informal or conversational style in language
the appeal of Wordsworth's colloquialism