überwiegend
predominantly
For the most part; mainly or chiefly.
Die Teilnehmer der Konferenz waren überwiegend Wissenschaftler.
The participants at the conference were predominantly scientists.

predominantly
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predominantly
For the most part; mainly or chiefly.
Die Teilnehmer der Konferenz waren überwiegend Wissenschaftler.
The participants at the conference were predominantly scientists.

'Überwiegend' (predominantly) is the present participle of the verb 'überwiegen'. This verb means 'to weigh more heavily' or 'to dominate'. So 'überwiegend' literally means 'having the most weight'.
Die Vorteile dieser Methode überwiegen deutlich.
The advantages of this method clearly outweigh the disadvantages.
Most of the time, 'überwiegend' (predominantly) is used as an adverb and then remains unchanged in the sentence. Less commonly, it is used as an adjective before a noun and then has to be declined.
Das Publikum bestand überwiegend aus jungen Leuten.
The audience consisted predominantly of young people.
The word 'überwiegend' (predominantly) belongs more to written language and factual contexts. It is often found in reports, news, or academic texts to describe a main tendency.
Die Exporte bestehen überwiegend aus Maschinen und Fahrzeugen.
The exports consist predominantly of machinery and vehicles.
mostly / most
'meist' and 'überwiegend' both say that something is true in many cases or for the most part. 'meist' fits especially well when something happens often or is usually the case. It sounds everyday and natural for habits. 'überwiegend' puts stronger emphasis on the larger share of something, for example in a group, a material, or an opinion. Learners may confuse the words because both express 'for the most part'. As a simple guide: for habits, you often use 'meist'; for proportions or composition, 'überwiegend' is more likely.

In diesem Kurs sprechen die Teilnehmer überwiegend Deutsch.
In this course, the participants speak predominantly German.
Nach der Arbeit gehe ich meist direkt nach Hause.
After work, I usually go straight home.