Oruga, the Spanish word for ‘caterpillar,’ developed from the synonymous Latin noun ūrūca. That Latin noun had another form, ērūca, and another meaning as the name for a certain plant in the cabbage (crucifer) family. The American Heritage Dictionary explains that it was “perhaps… so called from its hairy stems resembling caterpillars, or from the fact that cruciferous vegetables are often infested with caterpillars.” One name for that edible plant in English is colewort, the first part of which is a cognate of Spanish col ‘cabbage.’ Various other English names for the plant show an etymological connection to Latin ērūca—rucola, rucoli, roquette, (salad) rocket, and rugula. If that last seems almost familiar, it’s probably because of its better-known form in American English, arugula. Apparently that version of the word came from a dialect of Italian, as opposed to the rucola in standard Italian. Notice how standard Italian retained the k sound between vowels in ērūca, while the dialect picked up the voicing of the vowels that surrounded the k and turned it into a g sound. Spanish did the same thing as ūrūca became oruga.
© 2015 Steven Schwartzman