From DADBIZ this is a simple and small English/Spanish and Spanish/English dictionary, you can scroll through all the words by sliding up/down or writing the desired full/partial word and pressing "Search", consecutive pressing "Search" will advance to the next occurrence if any.
To search on words that start with what you type start then with a space!
Ex: " desa" only search words starting with "desa", uppercase and lowercase doesn't matter for the search.
To hear a speech in both languages press/select any listed entry.
(You need to have TextToSpeech installed with English and Spanish voices. Installed by default on most devices.)
It doesn't require internet connection.
The data for the dicitonaries come from:
http://www.wordgumbo.com/ie/rom/spa/idengspa.txt
http://www.wordgumbo.com/ie/rom/spa/fdengspa.txt
http://www.wordgumbo.com/ie/rom/spa/fdspaeng.txt