So for your own need and solving vocabulary problem you can install these free dictionary, here we go:
Top 7 English to Bangla and English to English Dictionary
Download link: Shoshi-English-To-Bangla-Dictionary
2.Bangla to English Dictionary
Download link: Bangla to English Dictionary
3. Download Free English to Bengali Dictionary for Your Java J2ME/Jar and Symbian Mobile Phones
E2BDictionadry Review :
Developer : MD. Waliul Islam from BUET, Dhaka, Bangladesh.
OS Support : JavaME/J2ME, Symbian(All).
License : Completely Free
E2BDictionary Home (English to Bengali dictionary for mobile phones)
Direct Download Link of E2BDictionary :Free English to Bengali Dictionary for Your Java J2ME/Jar and Symbian Mobile
4.Universal dictionary database Bangla to english Dictionary
Download link:Universal dictionary database
5.Best English to Bangla Dictionary of all time ( I personally loved this Dictionary)
Download link:Silicon Dictionary English To Bnagla
6.BanglaDictionary in portable version. No need to install just copy and paste the shortcut icon on your desktop.
Download link:Portable Bangla English dictionary
7.And lastly i have given a English to Bangla dictionary with vocabulary soft dictionary both download link are given below:
Donwload link:english to bangla dictionary
Download link:Vocabulary software