Resources concerning etymology and etymological roots of terms, expressions and idioms.
The Online Etymology Dictionary - Useful if you're trying to create your own plausible alternate terms.
StarLing Etymological Database - A very complete database with five millennia of reconstructed languages.
Alternate Terminology - Examples of alternate etymologies for various cultural and technological concepts, as seen in AH works and AH.com timelines and scenarios.
Alternate Geographic Names - Examples of alternate etymologies for various geographic names, as seen in AH works and AH.com timelines and scenarios.