buchstäblich
[…] Wiktionary distinguishes between them and gives ohne übertragene Lesweise as the meaning for buchstäblich (translation literally)
Fits pretty well.
ohne übertragene Lesweise – not in the figurative sense
Lots of words are often used figuratively, so are idioms. If you add buchstäblich, you mean it in the very literal sense.
Da musste er buchstäblich die Luft anhalten
Die Luft anhalten can be meant in a figurative sense, but by adding buchstäblich it's definitely the literal sense. It is not uncommon to leave out a clarifying buchstäblich to impart an ambiguous sense.
regelrecht
[…] and words like wirklich, wahrlich, geradezu for regelrecht (translation downright).
Regelrecht (when not used in the sense of proper/according to norms) usually introduces some kind of special expression, mostly giving a very vivid, demonstrative notion of what actually happened.
Der Gockel wurde von dem Fahrzeug regelrecht zerlegt.
Instead one might just say or write
Der Gockel wurde von dem Fahrzeug getötet/überfahren.
However, the first version uses the verb zerlegen, giving a very vivid image of what exactly happened to the Gockel.
wirklich
andwahrlich
are not good synonyms forregelrecht
. The semantic area covered bywirklich
is far greater andwahrlich
is old-fashioned language that no-one uses nowadays except for ironic effect. Better synonyms aregeradezu, nachgerade, richtiggehend
.