be certain(redirected from are certain)
To be sure (about something); to know definitively (that something will happen or is the case). A: "Yes, Michael's coming tonight." B: "Are you certain? It's already past seven, and he's not here yet." I'm certain that the stove is off—I double-checked it myself.
See also: certain
Farlex Dictionary of Idioms. © 2015 Farlex, Inc, all rights reserved.