Glossary entry (derived from question below)
English term
brooding
Obrigado.
Proposed translations
Brazil
IT, Games, Apps, Technical ENPT
Native in: Portuguese (Variant: Brazilian) 
Works in: English to Portuguese, Portuguese to English
taciturno
Brazil
Technical, IT and Marketing - Certified
Native in: Portuguese (Variant: Brazilian)
Works in: English to Portuguese, Spanish to Portuguese
acabrunhado(a)
Esperei anos para colocar essa palavra numa conversa/encontrar uma utilidade. Obrigado pela oportunidade.
Beijos
Brazil
IT Specialist • M.A. in Linguistics
Native in: Portuguese (Variant: Brazilian)
Works in: English to Portuguese, Spanish to Portuguese, Portuguese to English, and 1 more.
absorto
Como já tem "pensing" (pensativo) na frase, sugiro "absorto"
Ex.:
https://books.google.com.br/books?id=VfweAQAAIAAJ&q=pensativ...
Antero debruçou-se na varanda ao lado da irmã, pensativo, absorto, um ar de quem tem pecado às costas...
Brazil
Translator (4yr exp) / Lawyer (10yr exp)
Native in: Portuguese (Variant: Brazilian)
Works in: English to Portuguese, Portuguese
Meditativo
Brazil
Translator and Historian
Native in: Portuguese (Variant: Brazilian)
Works in: English to Portuguese, Portuguese to English, Spanish to Portuguese
abstraído
Will do!
Native in: Portuguese (Variant: European/Portugal)
Works in: English to Portuguese, French to Portuguese, German to Portuguese, and 1 more.
ensimesmado
Que tem a atenção voltada para o interior ou para os pensamentos.
https://www.infopedia.pt/dicionarios/lingua-portuguesa/ensim...
adjetivo
1. concentrado em si mesmo
2. recolhido
3. absorto nos próprios pensamentos; pensativo; meditabundo
Canada
Accuracy and A1 presentation
Native in: Hungarian 
, English (Variant: US)
Works in: English to Portuguese, Portuguese to English, Hungarian to English, and 13 more.
United States
Versed in English, Portuguese, Spanish
Native in: Portuguese (Variants: Brazilian, European/Portugal)
Works in: English to Portuguese, Portuguese to English, Spanish to Portuguese
deprimido
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Note added at 47 mins (2021-07-08 22:50:40 GMT)
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https://www.merriam-webster.com/dictionary/brooding#:~:text=...
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