Surprised that no comment mentioned that there is a standard term (not a word :P) for the set of words that denominates a particular concept: nominal syntagm. Such as "boiling water" and also "that green parrot we saw yesterday over the left branch".

Also the slider examples are abysmal. "I love you", "Go home" and "How are you" are not words by any stretch of imagination. For someone who makes word games, I don't see a particularly deep love of words here.

Edit: Obligatory reference to Borges's Tlön: https://en.wikipedia.org/wiki/Tl%C3%B6n,_Uqbar,_Orbis_Tertiu...

Added a note: "'I love you' isn't opaque, but it's tight enough to put on a tile." The familiar end of the spectrum picks up collocations that are transparent but loaded — I'm not claiming they're words in the traditional sense, but they're useful vocabulary for word games, which is where I'm coming from.