Und, aber, oder

A German dictionary will tell you that doch means but, however, yet, still, nevertheless, after all. That is six glosses pointing in several directions at once, and it is not the dictionary's fault. Doch does not translate. It signals.

These small words are the commonest in the language, and a learner meets them in the first week and is still slightly unsure of them years later. Worth taking properly.

The joiners

und is and, and carries more traffic than any other word on this list. oder is or. aber is but, and marks a contrast you can hear coming.

denn and weil both mean because, and they are not interchangeable in the way English speakers assume. Weil sends the verb to the end of its clause; denn does not touch the word order at all. A German who wants to keep a sentence simple reaches for denn.

The shapers

dass introduces a reported thought and pushes its verb to the end. wenn covers both if and when, which means German is sometimes ambiguous where English is not, and speakers live with it.

damit means so that, and it is the one on this list that most often catches a learner out, because it looks like it should mean with that. Sometimes it does. Context decides.

The particles, which are the real difficulty

doch, schon, noch, nur, auch, ja. These are the modal particles, and they are what makes German sound German. They carry no dictionary meaning worth the name. What they do is tell the listener how to take the sentence: as a correction, as an expectation confirmed, as impatience, as reassurance.

Doch in particular is untranslatable and indispensable: it is how you contradict a negative statement, which English cannot do in one word at all. If someone says you did not do it and you did, English needs a sentence. German needs doch.

You will not learn these from a list. You learn them by hearing them often enough that the wrong one starts to sound wrong, which is a slower and more reliable process than memorising glosses that were never accurate.