authenticated; solid; firm; real; true

accurate; exact; precise

definite; certain; fixed; to fix (on sth); to determine; to be sure; to ensure; to make certain; to ascertain; to clinch; to recognize; to confirm; OK (on computer dialog box)

indeed; really; reliable; real; true

to ensure; to guarantee

clear-cut; definite; explicit; to clarify; to specify; to make definite

really; indeed

to confirm; to verify; confirmation