To begin with...

http://www.inglesnosupermercado.com.br/vocabulario-de-eleicao-em-ingles-portugues/#axzz0xHkw8Ni3

http://www.proz.com/glossary-translations/english-to-portuguese-translations/62
http://www.proz.com/glossary-translations/
http://wordreference.com/pten/

 For more, use "Google Idiomas", and Portuguese-English Dictionaries, in print.

 Larousse "Dicionário avançado para o aprendizado da língua inglesa", or any other; it´s up to you to choose wich one you like most, and that fit your needs.

  We can help if you are puzzled with some particular term or expression, there are

teachers and advanced learners here that can give it a stab.