I'm not totally happy with this, but it's what I find in all transations of the German term and I can't do any better. In English, the term 'machine connector' is used (among other things) for a (relatively heavy duty) (ac) power connector (see first ref), but also for other types of connectors (see second ref). This also corresponds to German usage (e.g third and fourth refs).

In any case, it's definitely not a hot shoe, if only because you can't plug a hot shoe into anything...

refs:

1: www.glassnwood.com/components_m.htm

The Adapter Cord  is a standard IEC style cord with the 3 wires exposed. A wiring code is secured to each cord to allow your electrician to wire the appropriate machine connector to the cord.


2: http://www.idxinc.com/idx8.htm

Other special interface requirements are easily satisfied with new Personality Plugs designed specifically for the job. With the correct Personality Plug installed in the model X-10 or X-50 Xeptor, retrofit installation does not require any machine connector re-wiring!

3: www.elemot.de/p287.html

Schalter- Stecker- Kombination1~ mit Nullspannungsauslöser.
Maschinenstecker für 1~ Wechselstrom. Mit seitl. Ein/Aus - Schalter. ...

[with an accompanying picture of a heavy-duty female DIN AC power connector]

4: www.llt-lichttechnik.de/Ger/documents/d212bman.pdf

Lastausgänge Die Ausgangsspannung der Kanäle ist auf zwei
16 pol. Maschinenstecker herausgeführt ...