For simplicity's sake, let's assume that Wiktionary is licensed under CC-BY-SA 3.0, rather than also accounting for the GFDL dual-license.
The CC-BY-SA license does not prevent you from selling the original work, selling adaptations (derivative works), or selling collections that include the work. So you are generally fine.
However, you must license the adaptations under the same license. This has a couple of important implications:
- You must provide attribution of the content you used. As a minimum you need to mention the license and provide a link to the Wiktionary page. Ideally right next to the used content, not hidden in a settings page.
- You must not prevent others from sharing your adaptation, or modifying it further, or exercising any other rights the user may have under the license.
- You must not restrict use of your adaptations via DRM or other technological measures.
So while you can ask for a price, the fact that the content can be shared freely limits the economic viability of a business around this content.
A distinction should be made between a medium containing CC-BY-SA covered content, and a medium that itself is an CC-BY-SA covered work.
For example, the software in an app might be separable from the content in a database used by the app. That is, you can sell an app and a CC-BY-SA covered database for this app, but you must not restrict reuse of the content in the database.
Please be careful that any app store agreements you may agree to do not clash with the content license, which could be a problem if one agreement forces you to use DRM whereas the content license forbids this.
Some use of CC-BY-SA covered content might also be allowed by your applicable copyright laws, e.g. a right to quote or fair use. If your documents mainly consist of your own writing with a few Wiktionary quotes, the license may not apply. In contrast, if these documents just compile parts of the Wiktionary database that is certainly subject to the license.
You have no copyright for purely presentational changes such as typesetting the content or transforming it into some file format. If the content in a document/file is subject to the license, you should treat the entire document as subject to the license.