Bluepal's Dict-English Dictionary also passes the panjandrum test and falls well short in the interface and functionality tests. Misspell the word you're looking for, and you're out of luck. The app's unique light brown border and white-on-brown text distinguishes Dict-English from its competitors, but makes for tough reading. There is no way to adjust the type size. The November 17 update of Dict-English fixed a confusing design element of the app, which made its thesaurus the default setting. You need to click the settings button on the bottom right of the screen to switch between the dictionary and thesaurus.
Be advised that the thesaurus isn't very smart. Enter a word such as "maroon" and you will get a list of 96 words, beginning with "Titian," ending with "withdraw," and variables you may or may not be looking for, including "abandon," "cerise," "demask," and "ferruginous."
Ferruginous? Now there's a word I didn't know. It's almost as cool as panjandrum. But what does it mean? Something to do with iron, maybe. Just out of curiosity, I retyped it in Dict-English. The dictionary half of the app doesn't know what the thesaurus is doing. For what it's worth, Dictionaire, xyster.net's Dictionary, The Concise English Dictionary, and WordBook don't know what ferruginous means, either. My Shorter OED has it, though. In the context of the color maroon, the synonym ferruginous means "of the (color) of rust; reddish brown."
jDictionary Mobile's Concise English Dictionary knows panjandrum and about 1.6 million other words, terms, and people. I would compare it to the free Dictionaire app and judge it superior in terms of sheer volume. The app's interface looks pleasant, too--although, once again, there is no way to adjust the size of the app's display type. Why developers don't include such a feature as a matter of course is baffling to me.
You can browse the Concise English Dictionary by simply clicking the empty search field, although there is no A-Z scrolling function, so scrolling is a chore. But the search feature is fabulous and fast, and the app has forward and backward browsing. You can bookmark entries for future reference. And each entry includes hyperlinked synonyms.