EngDic is one of the best dictionary appication.and it contained 200 thousand word.

thsi dictionary contain seven engineering majors like:mechanic,materail,electronic,chemistry,industrial,civil and architecture
this dictionary prepared for engineering students to provide their english educations.

refrences:

1-McGraw-Hill Dictionary of Engineering Second Edition
2-ireb_cpre_glossary_14
3-Engineering_Glossary

this application provide with mohammad salehe alizadegan.