So, in no particular order, here are some terms that I think geospatial technology professionals and even non-technical managers might consider adding to their vocabularies.
modal - This is the term that prompted this list. A window or dialog box is said to be modal when you must dismiss it before continuing to use the software. The opposite is modeless. Modal windows are more common in the Windows environment while UNIX-based operating systems (including MacOS) tend to use modeless solutions. There are criticisms of both types of user interface solutions.
library - A collection of software commands and/or data used by the computer program that includes it. Said another way, it's a component on which end user software is built. If a library is missing or one with the same name from another program overwrote it (example), the software won't work correctly. Every now and again you'll see an error to that effect.
As an example, many GIS software packages depend on the Geospatial Data Abstraction Library (GDAL), which includes code for reading and writing image formats and vector formats (via the OGR library that's within GDAL).
open source - This is an approach to the design, development and distribution of software with a very specific meaning related to how the software can be distributed and used. It is not the same as "open" or "open API" or "open standard." Open source software licenses grant many rights (detailed and explained in this annotated definition); at the other end of the spectrum are proprietary software licenses, which grant fewer rights.
default - A choice that a software program automatically makes for the user, if the user does not elect to change anything. It's the way the interface (the menus and icons and the like) looks out of the box. It's the option that's highlighted in a dialog box automatically. It's the option that's executed when you hit enter. The best thing about defaults is that they can be changed! It's my experience that too few software users take advantage of the option to change the defaults to better meet their workflows.
client software - Software designed to communicate with a server (where data or functions are stored for use by the client). Client software can stand alone. For example, Microsoft Outlook is a mail client that connects to a mail server, and Google Earth connects to Google's servers to do their respective jobs. Alternatively, client software can be embedded in a browser, itself client software. Adobe's Flash works as a client-based software program, as does the Autodesk DWF reader. Thick clients (generally larger installs) do some processing and typically store some data locally, while thin clients (generally smaller installs) depend on the server for processing and storage and just show the results.
embed - Embedding refers to including someone else's video or music or document or app inside your website or blog. Embedding does not typically mean copying all the data to your server, but rather including some computer code that allows visitors to see and use the content on your website. This is commonly done with YouTube videos, podcasts, PowerPoint presentations (via SlideShare) or Word documents (via Scribd), but can also be done with some mapping programs, including Google Maps.