That which by the Seder on Pesach we eat "karpas", what does this word actually mean and where does it come from?
According to Jastrow, the word כרפס refers to an umbelliferous plant (one that has stalks branching out from a common stem, forming a flat or curved surface), like parsley or celery. It is not clear what the word's etymology is, or whether or not it is related to its homonym, כרפס, which turns up in Tanakh. That word, appearing in Esther 1:6, refers to a fine fabric, like linen (acc. to HALOT) or cotton (acc. to BDB). It is related to the Aramaic כרפסא and the Arabic كرباس (karbās), both of which derive from the Sanskrit karpāsa and the Greek καρπασος, meaning "cotton plant".
According to Rashi (cf: Genesis 37:3), this word is synonymous with פסים, which appears both as a reference to the clothes that Yaakov gave Yosef, as well as in 2 Samuel 13:18, in reference to the clothes that Tamar was wearing when Amnon sent her away. According to Rabbi Manoach ben Yaakov of Narvona (MT Hilkhot Chametz uMatzah 8:2), the reason that we dip this type of vegetable on erev pesach is to remind ourselves of the dipping of Yosef's coat into blood, which resulted in the servitude of his entire family and their offspring.
To make things short - I think it's just the vegetable's name.
I searched my Haggadot (one of them includes 12 perushim) - nothing. Wikipedia in Hebrew also doesn't explain the name's origin.
The only thing that comes to my head is that expensive fabrics are also called karpas in Meggillat Ester 1:6:
Could imply some connection to the plant, but I still think it's just its name.
One last thing, there's a known clue (Remez) in that name. the