This indispensable reference tool contains nearly 40,000 entries of terms used in the earth and environmental science literature. Long considered the definitive reference by geoscientists and other students and professionals needing fully supported and detailed definitions of earth science terms. Long published as a 800+ page hardbound book, the app version provides all of the rich content with the portability and power of searching the entire glossary. In addition to definitions, many entries include background information. The Glossary draws its authority from the expertise of the more than 100 geoscientists in many specialties who reviewed definitions and added new terms. This is a must-have for all geoscientists, engineers working with earth-related issues, and students and other professionals.

Special enhancements for this version of the app include:
* Full-text search
* Hyperlinked See-Also
* Flag and store terms
* Share terms and definitions
* Special access to AGI's GeoWord of the Day with a simple touch
* Search partial terms using wildcards (%)
* Browse by letter

What's New

Version 2.0.6

Update to fix issues with search in iOS 10.

Ratings and Reviews

Worth the money. Great information.


I use this every day at school. It’s a fantastic for geology students esp with a paperless workflow. If I hear a new word, I look it up with this app, screen capture it, copy the image and drop it right into notability. My only complaints are; it doesn’t search well with minor misspellings, and it needs a small update for the iPhone X user interface, (to fill the whole screen.) So far I’ve recommended the app to several people. I just wish It had a copy button to copy over a screen capture or maybe just drag a screen directly into notability somehow. Thanks and keep up the great work.

Great resource but poor execution


This app is expensive because it's a thoroughgoing scientific resource -- it's not a toy or an app for casual curiosity. With that in mind, I can say that the dictionary itself is a marvellous resource, but the app is a significant disappointment . I frequently find myself vexed when I try to use it - it seems to lose various functions randomly across uses (potentially across iOS updates, though I haven't tracked the breakages carefully). Currently, the search function is... functionless. Although the term "search" exists, no text box accompanies the prompt; accordingly, one cannot type in a word to search.

I wonder whether the frequent breakdowns occur because the app is offered by an organisation whose focus is geology, rather than IT and app development. Whatever the cause, the malfunctions are currently intolerable-- I spent quite a bit of money (relative to many apps) for something that should be invaluable, but is instead frustrating at its best and useless at its worst.

needs resizing

Brother Mikie

For the iPhone, it needs to let me move the partition between the word window and the definition window once I find the term I want. I looked up Facies and there are three column inches in the treekiller version which is a lot to read on an unsized window on an iPhone. Also, I'd like to be able to have it go back to the front cover somehow. It looks like I get to enjoy the design of that cover only upon the very first launch of the app. For the iPad, the problem is that when I find the term I want and hit Word List, it puts me back to A instead of all of the, e.g., Facies choices. Then when I go back to Search, my windows is blank again. The iPhone works correctly but the iPad does this blank thing.


American Geological Institute
128.8 MB
Requires iOS 7.0 or later. Compatible with iPhone, iPad, and iPod touch.
Age Rating
Rated 4+
© 2016 American Geosciences Institute


  • Family Sharing

    With Family Sharing set up, up to six family members can use this app.

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