Latin, a caterpillar; also, a sort of colewort.
eruca (plural erucae)
Part or all of this entry has been imported from the 1913 edition of Webster’s Dictionary, which is now free of copyright and hence in the public domain. The imported definitions may be significantly out of date, and any more recent senses may be completely missing.
From Proto-Indo-European *gher(s)-uka, from Proto-Indo-European *ghers (“to bristle”), see also Welsh garw (“rough”), Latin eris (“hedgehog”), Avestan zarshayamna- (“ruffling one's feathers”), Sanskrit हर्षते (“bristles”).
Latin erūca and its variant urūca denote the plant and the caterpillar. In such cases, usually the animal name is primary and has been extended to the plant (so the rocket can be interpreted as “caterpillar plant”).