How to invoke a KDE application with another language (equivalent of LANGUAGE=C)?

Invoking GNOME applications with LANUAGE=C application in a terminal seems to work fine (I've not yet experienced difficulties), I assume it is a specified (GNOME) behavior. What would be the equivalent way to controll language of KDE applications with a shell variable (not necessarily invoked in a KDE desktop, e.g. in Unity)?

The command

LANGUAGE=C application

is wrong. It may seem to 'work', but it's a coincidence.

LANGUAGE=X application

'works' too in that sense.

The LANGUAGE variable expects a colon separated list of language codes. Since neither C nor X is a valid language code, GNU compatible applications fall back to the original language, i.e. English.

LANGUAGE=en application

would be correct if LANGUAGE in the session environment is set to some other language, and you want to start a particular application in English.

To start non-GNU compatible applications in English you can use

LANG=en_US.UTF-8 application

KDE 4:

KDE_LANG=de myapp

KDE Frameworks 5:

LANGUAGE=de myapp

See http://techbase.kde.org/Development/Tutorials/Localization/Building_KDE%27s_l10n_Module Step 2: Test An Application