To accept that someone is telling the truth.
To have religious faith; to believe in a greater truth.
To accept as true, particularly without absolute certainty (i.e., as opposed to knowing).
To opine, think, reckon.
To take a customary action to ward off some misfortune that is believed to be attracted by a presumptuous statement.
Hopefully; a self-directive to undertake the customary action to ward off bad luck.