(1):

(adv.) Straight down; perpendicularly.

(2):

(a.) Open; artless; undisguised; absolute; unmixed; as, downright atheism.

(3):

(a.) Plain; direct; unceremonious; blunt; positive; as, he spoke in his downright way.

(4):

(adv.) Without delay; at once; completely.

(5):

(adv.) In plain terms; without ceremony.