Queísmo is a variation in Spanish grammar

Spanish grammar

Spanish grammar is the grammar of the Spanish language , which is a Romance language that originated in north central Spain and is spoken today throughout Spain, some twenty countries in the Americas, and Equatorial Guinea....

, considered wrong in prescriptive

Linguistic prescription

In linguistics, prescription denotes normative practices on such aspects of language use as spelling, grammar, pronunciation, and syntax. It includes judgments on what usages are socially proper and politically correct...

 works, when que is used instead of de que, en que, con que, etc. For example: No me enteré que estabas enfermo ("I was not aware that you were sick") is a case of queísmo, since the prescriptive construct is No me enteré de que estabas enfermo; the first sentence is typical of informal Spanish, the second one of formal or written Spanish.

Its symmetric phenomenon is Dequeísmo

Dequeísmo

Dequeísmo is a variation in Spanish grammar, considered wrong in prescriptive works, which consists in using de que instead of just que as the complementizer introducing a verbal complement clause. For example: Me dijo de que estaba cansado is a case of dequeísmo since the usual construct is Me...

, which is much less widespread.