I dony know, but chrono and Co. see the name lavos in the image of his day, and after, when you fight after magus, and fell into the portal to 6400000xxx ac, Gleen or the other say the word "lavos" maybe, ayla say this an call, lavos in reference, migthy la means fire (or big) but maybe means another one hundred of things, she and her tribe are just humans, semi-evolved, she learn new words when she know chrono, and his natural languaje has a tinny diferents words, maybe la, means all word that are closed to fire, like embers, lava, volcano, great meteorites, and more
The ones ho give the name to lavos are the zeal ones, and the people who live after the atack of 1999, find this information, and give the name of lavos to that big monster