Wanija Shabdakoshaya is a business-focused English-Sinhala word book from Sarasavi, handy for anyone dealing with trade, banking or office terms in both languages. Pair it with a quick English to Sinhala translation check for everyday phrases, and keep the high school English text books nearby if a student in the house is building vocabulary.
A glossary like this suits a commerce student or a small business owner, and when a contract or certificate needs official wording, certified Sinhala English translators can handle the formal side.