Having had to translate materials from Greek to (American) English (and vice versa) I have to agree that across-the-board definitions aren't available.
The cynic in me tends to think that we as academic feel we need to make our mark and thus we make up definitions for concepts that we think are new; on the other hand I do believe in polygenesis: that more than one person at a time have the same (or similar) idea and are working on it separately - thus the mushrooming of terms.
As a (rather newly minted) linguist it's still interesting to me to look at concepts intralinguistically and interlinguistically.
We ought to connect on linkedin and/or academia.edu (directed towards particiabts of this thread - posting from and iPhone , so I not sure where thus reply is actually going)