Hi All,
As macgyver points out, the word 'Steck' does not exist on its own in German. I have a vague recollection that at some point the term used in English-language catalogs for the building system was 'Plug and Click', and I think 'plug' is about the closest you can get as a one-to-one translation.
For example, a 'Stecker' is a plug, as in an electrical plug, and a 'Steckdose' is an electrical socket. In general, I think the verb 'stecken' covers the sense of 'inserting something into something else.' There are also a wide variety of German words where 'steck' is the root or base, but with a prefix attached, e.g., 'ausstecken,' which means to unplug something (like an electrical or computer cable).
There's plenty of similar sorts of examples in English of 'root' words that don't function on their own in modern usage. 'Forlorn' means sad and hopeless, but you don't use 'lorn' to mean happy and hopeful. Well, I don't, at least
Cheers,
AndrewL