TUAW reports that the Merriam-Webster’s Collegiate Dictionary, Eleventh Edition, is now available for the iPhone and iPod touch. Webster’s dictionary, converted to Apple’s handheld platforms by Paragon Technologie GmbH, now gives teachers, writers, and students a fully searchable reference at their fingertips.

This is a pocket version of the best-selling dictionary in the US, featuring over 225,000 defined words. Since it is a self-contained application and not a web front-end to an online dictionary, it can be used in situations where your device is in airplane mode.

Merriam-Webster’s Collegiate Dictionary sells for US$24.99 in the App Store. But of course carrying this app on your iPhone is a lot lighter than lugging around the US$23.95, 3.6 lb. printed version.

The other major competition to this application, Webster’s New World Dictionary (click opens iTunes) from AcroDesign, is a bit less expensive at US$14.99, but is less complete with only 163,000 entries.