The signification of the names of this day, except that of the Nahuatl calendar--_cohuatl_, "serpent"--appears to be uncertain. Perez says the word _chicchan_ can be explained only by considering it to be incorrectly written for _chichan_, "little." Henderson in his lexicon writes it _chichan_, and gives as the meaning of the word, "new, young, as _chichan u_, the new moon." Dr Seler first suggested that the first part of the name might be derived from the root _chi_, _chii_, "mouth, to bite," and hence that the signification might be "the biting serpent." However, he subsequently concluded that the proper interpretation is "a sign marked or taken," from _chich_, "a sign or mark," and _ch'aan_, "something taken or carried away." Dr Brinton thinks there is much less difficulty in construing it as _chich_, strong or great, and _chan_, the generic Tzental term for serpent. The generic term for serpent in the Zoztzil is _cham_.
Dr Seler does not attempt an explanation of the Tzental term, but Dr Brinton says that it means in that dialect and in Cakchiquel, "luck, fate, fortune." This, he says, is identical with the Zapotec _ci_, _zii_, and _guii_, and, as he finds evidence that the serpent is mentioned as an animal whence portents were derived by the Zapotecs, thinks this furnishes the connecting link with the signification in other calendars. This explanation is so circuitous, and in fact strained, as to render it unsatisfactory.
A study of the symbol with reference to its origin may perhaps furnish some aid in arriving at the true signification of the name. As will be seen by reference to the various forms of the symbol, the bordering of the circular inclosed space appears to be more permanent than the inner markings. This is apparent from the fact that the little squares or blocks are retained in all the types except the anomalous forms shown in plate LXV, 16-18, and even in one of these (LXV, 18) they appear. On the other hand, the markings in the inclosed space are varied, and in some instances, as LXV, 11, are omitted altogether. It would seem, therefore, from this that the bordering was considered the essential element of the glyph. From what, then, is the symbol taken? If we turn to Dresden 25c, we see in the priest's robe, in all probability, that from which the symbol was derived. Here we have the inner crosshatching and the little dark blocks or squares around the border. The same pattern is seen also on Tro. 16*b and c, and on the female dresses, same codex, 20*c and d. On the latter, in some cases, is the waved line seen in the unusual forms of the day symbol shown in plate LXV, 17, 18, and 19. Other examples could be referred to, but attention is called only to one more, viz, the curtain-like articles exhibited on Tro. 29*b, where we see not only the inner crosshatching and bordering blocks, but on the side borders the precise marking of the day symbol shown in plate LXV, 17.