WordWeb Online

1. Thoroughgoing
   "he is downright dishonest";
   - outright

1. Characterized by plain blunt honesty
   "a downright answer"; "a downright kind of person"
    
2. Complete and without restriction or qualification; sometimes used informally as an intensifier
   "a downright lie";
   - absolute, out-and-out, rank, right-down, sheer, down-the-line [informal]

See also: complete, honest, honorable [US], honourable [Brit, Cdn]