Forthrightly and Flat-out

Forthrightly adverb - In an honest and direct manner.

Flat-out and forthrightly are semantically related. In some cases you can use "Flat-out" instead an adverb "Forthrightly".

Flat-out adjective - Having no exceptions or restrictions.

Forthrightly and flat-out are semantically related. Sometimes you can use "Forthrightly" instead an adverb phrase "Flat-out".