Native speakers of standard Spanish, like those of standard English, are unlikely to recognize traila. The word is an example of Spanglish, or some would say Tex-Mex. By whatever designation, traila is a Spanish version of the English word trailer. While traila can refer to the type of trailer that people live in, which is to say a mobile home, when I saw the word in Austin the other day it appeared on the side of a vehicle from which people buy breakfast or lunch, i.e. a food trailer.
English trailer obviously comes from trail: a trailer is a vehicle that trails behind the one that is pulling it. The etymology of trail itself isn’t fully established. The American Heritage Dictionary says that Middle English probably took the verb trailen, source of the modern trail, from Old French trailler, which meant ‘to hunt without a foreknown course.’ That would have developed from Vulgar Latin *trāgulāre, a hunting term meaning ‘to make a deer double back and forth.’ The AHD speculates that *trāgulāre might have arisen as an alteration of Latin trahere ‘to pull, draw,’ under the influence of Latin trāgula ‘dragnet.’ In trahere, of course, we recognize the ancestor of the synonymous Spanish traer, which according to linguasorb is the 73rd most common verb in Spanish (follow the link if you’d like to see a list of the top 100).
© 2016 Steven Schwartzman