enallage (rhetoric)
Definition - Substituting grammatically different but semantically equivalent constructions.

Note: Sometimes a grammatically incorrect substitution is made to add emphasis.

Example -
We was robbed!

Etymology -
The word means "change" in Greek

Oxford English Dictionary -
Its first citation in its rhetorical sense is from 1736:
"Enallage, a figure whereby we change or invert the order of the terms in a discourse."

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