I discern between regular adverbs and modal particles, but there is some fuzzy areas for me to figure out. I would like a native speaker's feel for it said here. My definition is grammaticalization and frequent usage of these words compared to optional usage. English has the variability of using particle like words, but it is limited and not mandatory. In English one can say "He has BUT left" ("He has done anything but leave, all those other things, yes, but not that."), you can argue this modifies the meaning of the verb, but that too is fuzzy as adverbs in German are completely uninflected, so is it the transition of a non-adverb word into a different usage and a stronger meaning part of the equation? I see conjunctions and certain prepositions as modal particles, but aren't there words with multiple usages as in English (well as an adjective vs adverb) This is from wikipedia for "aber" the rough translation of "but" Du sprichst aber schon gut Deutsch! ("On the contrary, you speak very good German!") The above is not directly translatable but: Ich war schon auf der Party, aber Spaß hatte ich nicht! ("I was indeed at the party, but fun I had not!.") This is confusing for me.